NATURAL HISTORY BOOKS.*
Sirvmskr., noteworthy books for naturalists have appeared within the last few months. In a massive and finely illus- trated volume Mr. Gerald H. Thayer expounds his father's theories and discoveries relating to Concealing-Coloration in. the Animal Kingdom. The subject is supremely interesting, and the material collected by these two American naturalists, when it has been sifted, is of the very greatest value. Mr. Abbott H. Thayer's discovery is "the law of obliterative shading " ; which means that an animal secures invisibility by being darker above than below. Something of the sort had been pointed oat by Professor Poulton, of Oxford, in connexion with caterpillars. But having obliterated the outline, in a manner familiar to all who have studied the amazing models of counter-shaded ducks at the Natural • (1) Concealing-Coloration in the Animal Kingdom: being a Summary of Abbott H. Thayer's Discoveries. By Gerald H. Thayer. Illustrated. London, Macmillan and Co. [Ks. 6cL net.]—(11) The Vertebrate Fauna of Cheshire and Liverpool Bay. Edited by T. A. Coward, F.Z.S. With Illustrations from Photographs by Thomas Baddeley. 2 vols. London : Witherby and Co. [26a. net.3—(3) A History of Birds. By W. P. PycraIL With an Intro- duction by Sir Ray Lankester, and Numerous Illustrations and Diagrams. London Methuen and Co. [10s. 8& net.]—(4) Indian Birds: being a Keg to the Common Birds of the Plains of India. By Douglas Dewar. London John Lane. [6s. net.]—(5) The Birds of Burma. By Major H. H. Harington, M.B.O.U., F.Z.S. Rangoon: Rangoon Gazette Press.— (6) Eggs and Nests of British Birds. By Frank Finn, B.A. (Oxon.), F.Z.S. With Coloured Repro- ductions of 154 Eggs from Nature in 20 Plates and with Reproductions of 74 Eggs in Half-tone, and other Illustrations. London: Hutchinson and Co. [5s. net.]—(7) Ants: their Structure. Development, and Behavior: By William Morton Wheeler. Ph.D. New Turk: The Columbia 'University Press. 5 dollars net.) History Muse-um., 'it becomes necessary to supply background picturing. Many animals have markings which clearly fit their backgrounds. Mr. Thayer is a believer in natural selection pure and simple and omnipotent. He distinguishes carefully between protective colouring which renders an animal invisible and mimicry which makes an animal look like something else. He also dwells on what many overlook, that a coloured or boldly marked animal is seen by its prey and its enemies from a different level and aspect from that from which the human eye regards it. To Mr. Thayer all colora- tion in the animal kingdom is developed to secure invisibility; and having by his argument and ingenuity carried most naturalists with him up to a point, he turns them into antagonists by pressing his theories too far. When we are told that bold colouring really conceals, and that all dazzling patterns are fundamentally obliterative, we feel the need at lcast for time for consideration. Of sexual selection Mr. Thayer is supremely contemptuous in so far it is put forward as a theory for explaining the brilliant plumage of male birds. The nuptial plumes of egrets are to mould the body and obliterate shadows. Of warning coloration he will hear nothing ; and the white of the skunk's back serves to imitate the shining sky seen by small animals on the ground. The white rumps of antelopes and rabbits "blot out" the body. All this is argued with an ingenuity and a profusion of photo- graphs, facts, and observations that almost overwhelm and convince the reader. At last one pauses to ask whether the facts are not being fitted to the theory. The chapters on "secant" and " roptive" markings have already been hard to swallow. The plates of the boldly marked or coloured oyster- catcher and tit are unconvincing. The black heads of gulls are " ruptive marks." The black marks on their quill feathers are "distractive marks." Iridescence and the strange appendages of many birds all work towards concealment. The climax is reached when magpies are spoken of as "picturing snow-shadows and fir foliage." Yet the book is a fine piece of work and a valuable contribution to zoology ; but it must be studied critically. The illustrations are splendid, and the text will be understood and appreciated by those who are not necessarily real students of zoology.
In The Vertebrate Fauna of Cheshire, edited by Mr. T. A. Coward, we have another of those complete and detailed local natural histories of which British zoologists have good reason to be proud. The two finely printed and well-produced volumes are a pleasure to handle, and contain a mass of information only to be collected by much painstaking. In some ways Cheshire is not a very interesting county to naturalists. Much of its natural beauty has been horribly disfigured and its rivers are sadly polluted. It lies rather of the migration routes of birds and its coastline is not exten- sive. In the present case the whole of Liverpool Bay, embracing the estuaries of the Dee and Mersey, is included. The list of cetaceans is short; but Mr. James Johnstone, who is an authority on fisheries, has undertaken the marine and sea-water fishes. Besides a list, with notes on the fish which have occurred, be contributes a dozen pages on the conditions prevailing in the Cheshire sea area. So little is known about the life-histories, habits, and migrations of sea fish that this addition to a local fauna is worth attention. Too few "field naturalists," if one may call them by that name, devote any attention to fishes, and too many are seduced by the attractions of birds. The first of Mr. Coward's volumes opens with a general descriptive introduction, followed by a few notes on the effects of game and for preservation. In writing on the mammals and birds he has had the assistance of Mr. Charles Oldham, a well-known Cheshire naturalist, and his collaborator ten years ago in a book on the birds of the county. The Lyme Park cattle, Which became extinct in 185, were a link with the past, and some facts of interest are also given on the much less familiar herd at Somerford Park. The second volume has a chapter on "The Dee as a Wildfowl Resort" by Mr. John A. Dockray, who writes with twenty years' experience, and has collected information from those whose memories go much further back. Wild swans still visit the Dee. Barnacle geese have deserted the estuary ; brent are not uncommon; grey lag and bean are rare; but pink-footed geese are numerous and increasing in numbers. Reptiles and amphibians as well as fish are included in the second volume; there is also a full bibliography, a county map, and, scattered through the two volumes, a number of photographs. With this scanty
description of the immense amount that will be found of interest in these two volumes we must rest content, and pass on to another work which is wholly devoted to ornithology.
The ideal which Mr. W. P. Pycraft has set up in writing A History of Birds is an excellent one. His book is the first of a series of four volumes on animal life which are to form an evolutionary natural history. The aim is to be com- mended because there are too many merely descriptive and systematic writers who pass over the deeper problems on which a study of birds throws light. Baaring this in mind, Mr. Pycraft discards the usual order, and dwells on the reptilian ancestry of birds and the modifications of structure which the class Ares present at this day. He treats also of the problems of geographical distribution, migration, parasitism, relations of the sexes, and reproduction. He has chapters on variation, and on natural, artificial, and sexual selection. In these he discusses various new ideas, and shows to what extent Darwin's views on the struggle for life and its effects still hold the field, and where they are open to criticism. Of special note are Mr. Pycraft's remarks on the study of nestling birds, to which be has given particular attention. It is a subject that may teach nearly as much about birds as embryology has taught about the evolution of mammals. Mr. Pycraft writes with such a wealth of knowledge, and has such a mass of facts at his command, that he sometimes forgets to pause and explain in untechnical language the significance of the adaptations of structure which he describes. He does not profess, so be tells us, to write a book for "experts," but the most eager inexpert general reader may well be pulled up by such words as Pelargocolymbomorphine," "emphysematous," or " diastataxic." Some of• the many similar words, in which Mr. Pycraft appears to revel, will be unfamiliar even to a scientific ornithologist, and the meanings of a number are not explained. In a book of this nature it is a mistake to employ more technical terms than are absolutely necessary. Why, for instance, introduce the word " eedysis " at all when " moult " will serve the purpose P Mr. Pycraft, even though he is writing for those who are not "experts," seems to forget that most of his readers will know much less than he does, and that it is possible to explain the deepest problems of biology in simple, clear, and ordinary language. The facts and conclusions of zoology are not difficult to understand. Technical terms are but symbols, and of no value in them- selves, though exceedingly useful. It is far better that the reader should understand the actual structure of birds' wings than become familiar with the word " aquinto-cubitalism." The illustrations of Mr. Pycraft's book are exceedingly good, but their value would be much increased if under each were printed a short and clear explanation of the lesson to be taught or the fact intended to be illustrated. The index might also with advantage have been made more complete. These criticisms go to the form and not to the substance of Mr. Pycraft's work. He has produced an original, com- prehensive, and learned work on birds containing much that is not otherwise easily accessible, but in certain respects dis- appointing. It is needless to add that he writes as an authority worthy of respectful attention, and that his position in the Zoological Department of the British Museum has given him special advantages of study. Of particular interest on this account is the chapter entitled "Phylogenetic," in which he endeavours to trace the main lines along which birds have been evolved. The subject touches so much that is speculative that authorities as great as Mr. Pycraft will be found contending in favour of almost contrary views. One lays down a book of this nature more than ever impressed with the mass of work still to be done, in spite of the vast additions to our knowledge of ornithology in recent years, and Mr. Pycraft himself frequently points out fields still open to patient and careful observers.
Two small books dealing with Indian and Burmese birds respectively may be noticed next. Indian Birds is by Mr. Douglas Dewar, a charming writer, whose earlier books on birds we have had the pleasure 'of recommending. The present volume is, however, severely practical, and is described as a " key " to the common birds of the plains of India. By selecting conspicuous characters Mr. Dewar aorta out the birds, and then, having reduced the groups into small classes, he gives a few notes on appearance and habits which will enable the identification to be completed. The book is most
carefully compiled, and much ingenuity is displayed in framing this artificial 'analysis. As a companion to larger works we believe it will be useful to the Anglo-Indian field naturalist or tourist. Mr. Dewar, like Major H. H. Harington in his Birds of Burma, omits the game-birds and waterfowl. Major Harington's aim is a153 to enable those who are observant to recognise the various birds that are likely to be seen. His descriptions are short, characteristic, and written with those apt words which mark a field naturalist's familiarity with the bird's look and ways. There are no technical descriptions, but the salient features of the plumage are mentioned. Some of the notes have appeared in the Rangoon Gazette. The latter half of the volume is devoted to tables showing the distribution of birds in the various Burmese districts.
We may also recommend a small and handy volume by Mr. Frank Finn on the Eggs and Nests of British Birds. The coloured plates are effective; the text, though short, is, so far as one can test it, trustworthy. No systematic order is followed, which we venture to think a misfortune, for it is impossible to make a reasonable division between birds which nest in towns and gardens and those which nest by waysides and woodlands. The arbitrary grouping of the eggs in the plates is dictated by considerations affecting the tricolour process. There are also uncoloured photographs of a number of nests and nestlings, and notes at the end of the volume on birds which visit these islands but do not breed here.
Lastly, we have but insufficient space left to notice the most thorough and complete treatise on Ants : their Structure, Development, and Behavior, which forma the ninth volume in the well-known and excellent" Columbia University Biological Series." So far as we know, there does not exist any work in the English language which deals in so comprehensive a fashion with myrmecolog,y. The author is Professor William Morton Wheeler, of Harvard, a well-known American entomologist, a high authority and most diligent student. His massive book is well illustrated with a profusion of figures, and the bibliography of seventy pages will astonish those who are not familiar with the literature on ante. Many chapters on structure and classification are highly technical, but a great deal of the work which treats of habits and intelligence or instinct will be found of absorbing interest to readers whose knowledge is superficial Ants and men have developed from their common ancestor along different lines. Each has become a dominant animal,—man among mammals and above ground, ants among insects and in the sub- terranean world. This view of ants is beautifully developed by Professor Wheeler.
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