i8 9 6. SOME NEW BOOKS. 269 



majority of known fishes. The Crossopterygian and Actinopterygian 

 orders are separately treated, but otherwise there is no definite 

 systematic classification. A good series of figures of representative 

 recent fishes are copied chiefly from Giinther and Goode ; while most 

 of the figures of fossil forms are well-chosen, excluding only those of 

 Gyroptyckius, Osteolepis, Elonicktkys, Catuvus, and Leptolepis, which are 

 very erroneous, having been drawn by Pander and Agassiz many 

 years ago, when comparatively little was known of the genera they 

 represent. 



Chapter viii., on the Development of Fishes, is especially valuable 

 as containing much new matter with good illustrations, and as being 

 the first general synopsis of its kind. The development of the egg 

 and early embryo is successively described in the lamprey, the 

 shark, Cevatodus, Acipenser, and a Teleostean. This line of research, 

 however, affords much less important information concerning the 

 evolution of fishes than was formerly expected from it. Dr. Dean 

 rightly laments that all deductions from the embryology of fishes are 

 as yet very inconclusive. " The majority of the forms, including some 

 of the most important, are developmentally unknown ; yet sufficient 

 is known of the representative members of the groups to show the 

 most perplexing characters. On the one hand, the developmental 

 processes of forms which are regarded by the morphologist as closely 

 akin seem often widely distinct ; and, on the other hand, the fishes 

 which should, a priori, exhibit an archaic mode of development, 

 actually present complex processes of early growth which can only be 

 interpreted as highly specialised. In fact, there are far greater 

 differences in the developmental plans of the closely-related Ganoid 

 and Teleost, than in those of a Reptile and a Bird ; and even among 

 the members of the single group, Teleosts, there are more striking 

 embryological differences than those between Reptiles and Mammals. 

 Adaptive characters have entered so largely into the plan of the 

 development of fishes that they obscure many of the features which 

 might otherwise be made of value for comparison. And until the 

 controversies regarding some of the most fundamental principles in 

 embryology — e.g., the importance of the loss or gain of food yolk — 

 shall be decided, it seems impracticable to use the plan of develop- 

 ment as in any strict sense a guide in phylogeny." 



The last sixty pages of the volume are devoted to a list of deriva- 

 tions of proper names, a copious bibliography, and a series of illustrated 

 tabular statements of the anatomical characters of the great groups of 

 fishes. These sections bear signs of having been prepared most care- 

 fully and laboriously, and form an admirable appendix for purposes of 

 reference. There will be much difference of opinion among specialists 

 as to the value of some of the tables and the judgment pronounced by 

 the author ; but we have detected a very small proportion of errors 

 for so bold an enterprise, and students of the lower vertebrata are 

 much indebted to Dr. Dean for an invaluable compendium. To 

 criticise the result in detail would be ungrateful, and we would only 

 allude to two points. Like too many authors of the present genera- 

 tion,. Dr. Dean entirely ignores the unrivalled mine of information con- 

 tained in Owen's "Anatomy of Vertebrates" and his Catalogues 

 published by the Royal College of Surgeons ; even Stannius is unac- 

 countably omitted from the list of general works on the anatomy of 

 fishes. Secondly, the drawings ought all to be strict copies of nature, 

 and not provided with embellishments to favour any particular theory, 

 such as happens in the case of fig. 313 (skull of Ceratodus) where a 

 non-existent suture is introduced to justify the nomenclature adopted. 



