158 SOME NEW BOOKS [febri im 



especially the Purbeck and Conio types as representing onlj Monotremes and 

 Marsupials; and from this we infer thai be considers the Eutheriaor Placentals 

 of comparatively late origin, A fewerrors bave found their way into the treat 



incut of tin' mammals, which may be corrected in a later edition. The teeth of 



\ne\lo|H>da (page 307) are said to resemble those of the Rhinoceros. This is 



evidently incorrect, as they stand nearest the teeth of the Titanothcres. and 



hence of the Artiodactyls, Erroneously, we believe, the author follows Lydekker 

 and Flowerin placing all the early Perissodactyla among the Lophiodontidae, 

 disregarding the fad that in the Lower Eocene all the modem families oi 

 Perissodactyls are sharply defined. This leads to a further confusion in 

 reference to the family Palaeotheriidae, which is said to approach the Rhino 

 ceroses, The conception of the family distinctness oi early ungulates agrees 

 with that held by the author himself in his treatment oi the Fishes, namely. 

 that family lines should correspond with phyla, and not with the parallel 

 assumption by distinct phyla oi similar characters, 



One oi the most remarkable things about this work is, that the author 

 appears to be less clear and logical in the major classification of the Fishes, his 

 own special field oi work, than he is among the Reptiles. This appears io arise 

 from far too great reliance upon the lines drawn by Keichort and Huxley 



between u autostylic " and "hyostylic" types, and from setting aside the really 

 fundamental characters oi division between cartilaginous fishes in which true 

 bone is absent, and Tcleostomcs and Ibpnoans, which have more or less true 

 bone. Single characters, such as the suspensorium, may be safely employed in 

 major classification, provided first that they are not acquired by parallelism, and 

 second that they really afford sharp and natural lines of division. Hyostylism 

 and autOStylism answer neither oi these criteria. The Klasinobranchs are 

 grouped by the author as hyostylic (p, 27), although members oi this subclass 

 show every stage oi transition between autOStylism (Hrptanchus) and hvo 



stylism (Jftya). These transitions are obviously adaptations to feeding habits. 



analogous to those which we observ e among reptiles with a loose or swinging, 

 and tight or firm, articulation for the angle oi the lower jaw. The autostylic 

 Chimcura, with its firmly united upper jaw ami reduced hyomandibular, i- 

 adapted to a mode oi feeding upon small molluscs and crustaceans not \ cry 

 dissimilar from that of the lizard SphenodoH, in which the iood is firmly seized 

 by the anterior teeth and cut up by the molar plates. The loose and swinging 

 shark jaws, with the hyomandibular acting as a supporting bar. are to be com 

 pared with those oi snakes, in which the mouth is very expansible, and the food 

 is swallowed whole, the backward pointing teeth serving to prevent escape. 

 Moreover, these terms are misapplied by the author not only in sharks, but in 

 other specific cases. The Crossopterygians (p. 69) are defined as " hyostylic M 

 y .\ character by the way which would seriously interfere with their position 

 among the ancestors oi the pronouncedly autostylic Amphibia), and this is an 

 error, for. as observed by Pollard, "On examining the hyomandibular it will be 

 seen that it can take very little part in the suspension oi the jaw s."' 



We thus conclude that a close examination oi the suspensorium of all the 

 Living and extinct fishes proves that "auto-," "hyo-," and " amphistylism * are 

 at the most ordinal characters, and cannot take rank as sub class characters, 

 except in the definition oi the Dipnoi, Even then some oi the orders are 

 susceptible to adaptive modification, and thus do not present those sharp and 

 fast lines oi demarcation which are necessary for ordinal definition. To return 

 to C : . I '. it is obvious that, so far as the concrescence oi the palatoquadrate 

 oi the skull is concerned, this condition could readily be derived from that seen 

 in the Notidani v //< 'ptanchus) simply by fixation, and after carefully comparing 

 all the other characters which are assigned by the author to give C/n'iitiunt and 

 its allies a subclass position, among the Holooephali, we find that they are no 

 greater than those which give the Acanthodii and Pleuropterygii their ordinal 

 position, Upon these grounds we conclude that the scheme oi major classifies 



