May 17, 1888] 



NATURE 



5i 



tinuous advance." Past and present organic life, as 

 Darwin himself carefully pointed out, are combined, not 

 in a continuous chain, but in a genealogical tree: "evo- 

 lution recognizes modifications in the most divergent 

 directions, and the tree of life that it restores is not a 

 straight stem growing from a continuous apical bud, but 

 a stem, or possibly even a limited number of stems, 

 branching in varying directions." Thus the progress 

 among organic beings is analogous to that in the develop- 

 ment of civilization. " The united world advances, whereas 

 individual tribes or nations remain at a standstill, or even 

 degenerate and decay. Such is precisely the history of 

 the organic development of our planet : new and more 

 complicated organic types are being continually evolved, 

 but side by side with these forms we still meet with those 

 of a lower grade of organization, while still others, 

 belonging to the earlier periods of the world's history, 

 have completely dropped out." 



After a brief sketch of the first appearance of vertebrate 

 life, Prof. Heilprin describes the relations of the fishes, the 

 amphibians, and the reptiles, indicating the affinities of 

 the first and second, which have led Prof. Huxley to treat 

 them as sub-groups of a single division, the Ichthyopsida. 

 In the structure of the heart, mode of breathing, and 

 nature of circulation, the young frog agrees with a fishj 

 while in these respects the mud-fishes (Ceratodus) agree 

 with the amphibians. Now this link between these great 

 groups exists in very early times, as the hypothesis would 

 demand. " Dipterus and its allies are fishes that belong 

 to the Devonian period of time," and Ceratodus itself was 

 living in the Permian, and thus " represents the oldest 

 living vertebrate type known to naturalists." The peculiar 

 structure of the teeth of the labyrinthodonts, found also 

 in some of the earliest fishes, and still retained by the 

 alligator-gar, is another link. Next, in regard to the date of 

 the appearance of birds and mammals, which is sometimes 

 regarded as rather anomalous, Prof. Heilprin points out 

 that both the earliest birds and the earliest mammals 

 have marked reptilian affinities, which in the former are 

 very distinct, so that such forms as Archcsopteryx and 

 some of the early dentigerous birds on the one side, and 

 the Pterosauria on the other, do much to link together 

 the two classes. Further, the ancestry of the non-flying 

 birds, such as Dinornis and its allies, may be traced 

 with greatest probability to members of the Dinosauria, 

 such as Iguanodon, Hadrosaurus, and Compsognathus. 

 In like way the affinities of the monotremes with the 

 reptiles are pointed out, and attention is called to the 

 significant fact that " the earliest reptilian forms — those 

 of the Permian period — are the only animals which possess 

 the remarkable dental characters of the Mammalia." 



In the second section of the book Prof. Heilprin deals 

 more especially with the development of the Mammalia 

 themselves, instancing the position occupied by the 

 Eocene Creodonta between the now widely divergent 

 Carnivora and Insectivora, the relationships among the 

 groups of the former, and of the latter to the lemurs, the 

 well-known pedigree of the horse, the ancestry of the 

 hornless ruminants, the development of the horns of the 

 deer, from the simple forked crown in the early Cervines 

 of the Middle Miocene to the complicated forms assumed 

 in the Pliocene and more recent times. Cervalcas 

 ■americanus, the newly-discovered link between the 



Canada stag and the elk, also receives notice, as does the 

 relation of the homocercal and heterocercal to the 

 primitive diphycercal fishes. Attention is also called to 

 the development of the brain in various vertebrates. 



In the third section the author glances at the question 

 of the antiquity of man. In regard to some of the alleged 

 evidence he exercises a wise scepticism, and states that 

 up to the present time he has been unable " to find satis- 

 factory proof of man's belongings having been found in 

 deposits very much (if at all) older than the Post-Plio- 

 cene," though he thinks it not unlikely that such may 

 ultimately be found. In connection with this subject he 

 mentions some human vertebrae, mineralized by limonite, 

 of unknown but evidently high antiquity, discovered by 

 himself in Florida. 



Lastly, he calls attention to a class of evidence which 

 the comparative persistency of conditions in certain parts 

 of the United States has rendered accessible to American 

 geologists — namely, the relation of living forms to their 

 more immediate predecessors. Instances of this may be 

 obtained in the sheltered regions of the Gulf of Mexico 

 and in the comparatively modern rocks of the Florida 

 peninsula. As examples, species of the genera Strombus, 

 Voluta, Fulgur, and Melongena, are figured, showing the 

 gradual transition from an extinct to an existing species, 

 and to these are added a group of Paludinaa from the 

 Middle Tertiary of Slavonia, illustrating successive varietal 

 and specific forms. 



The book is attractively written, though we must 

 venture to protest against two instances of American- 

 English : " The swift-footed animal . . . elevates the 

 body so as to weight it principally upon the extremi- 

 ties of the toes ; " and " the evidence is . . . but a 

 mere figment of that which pertains to zoology." The 

 first gains so little that brevity can hardly be pleaded as 

 its excuse ; the second, unless a misprint, is worthy of 

 Mrs. Malaprop. T. G. B. 



THE SHELL-COLLECTOR'S HAND-BOOK FOR 



THE FIELD. 

 The Shell-Collector's Hand-book for the Field. By J. W. 



Williams, M.A., D.Sc. Small 8vo, pp. 148 (interleaved). 



(London : Roper and Drowley, 1888.) 



HANDY books for collectors, whether of birds, beasts, 

 fishes, mollusks, or other organisms, are always 

 most acceptable when well put together and carefully 

 contrived, even if they be not original. The present little 

 book might at first sight lay claim to having fulfilled all 

 these conditions. It is small enough for the pocket, and 

 the type is clear and legible ; but when we enter upon the 

 work itself, alas ! we do not find our dream of a typical 

 collector's hand-book realized by any means. Chapter I. 

 "The Anatomy of a Snail," and Chapter II. "The 

 Anatomy of a Fresh- water Mussel," should have 

 been altogether omitted. They are not cleverly com- 

 piled, they are sadly full of mistakes, and these too 

 clearly betray the fact that the author himself is not 

 familiar with Mollusca from an anatomical point of view, 

 but rather has got up his subject after the style of " Cousin 

 Cramchild." Thus, the colour of the shell (says Dr. 

 Williams), exists entirely in the periostracum or epi- 

 dermis. We would advise the learned author to try and 



