244 



NATURE 



[July i6, 189: 



fore fail to see his reasons for adopting the antiquated 

 classification. 



Some of the most interesting chapters in the volume 

 are those devoted to the evolution of the Echinoderms, 

 the author adopting Neumayr's view that the Palaeozoic 

 Blastoids, as well as Crinoids, Sea-Urchins, and Star- 

 fishes, are all separate branches springing from the 

 Cystoids of the Palaeozoic. * The figures illustrating the 

 gradual specialization of the Sea-urchins from the old 

 Palasoechinoids, with their numerous rows of interam- 

 bulacral plates, through the Triassic Tiarechinus, and 

 thence to the Neocomian Tetracidaris, with its two rows j 

 of apical interambulacrals splitting into four near its 

 equator, and thence to the modern "regular" Urchins, I 

 strike us as particularly well selected. Equally instruc- 

 tive is the transition from the " regular " modern Urchins 

 (Neoechinoids) to the "irregular" forms— at first with the 

 retention of the masticating apparatus, and subsequently 

 with its loss. 



Merely noticing that full justice is done to Neumayr's 

 views regarding the phylogeny of the Brachiopods, we 

 pass to the MoUusca, which we find treated in consider- 

 able detail and well illustrated. The author adopts the 

 modern view of separating Dentalium as a distinct order 

 (Scaphopods) from the Gastropods, and considers that ! 

 both Pelecypods (Bivalves) and Scaphopods are derived 

 from the latter. Nothing is 'said as to the origin of the 

 Gastropods themselves, or, indeed, of the Cephalopods — 

 probably for the very sufficient reason that nothing definite 

 is yet known. In regard to the mutual relations of the 

 various groups of Cephalopods, the author comes to the 

 conclusion that the Ammonites should form a distinct 

 order, " Ammonoidea," to be placed between the Tetra- 

 branchiates (Nautilus) and Dibranchiates (Cuttlefish). 

 Since, however, he adopts the view that their shells 

 were really external, and that they are probably de- 

 scended from Nautiloids, there seems but little necessity for 

 this third order. The gradual increasing complexity in the 

 sutures as we pass from Goniatites to Ceratites, and from 

 the latter to true Ammonites, is held sufficient to prove 

 the descent of the latter from the former ; while Goniatites 

 are considered to be the direct offshoots from Nautiloids, 

 which are themselves derived from straight forms like 

 Orthoceras. It would require too much space to enter 

 on the consideration of the relatione of the various genera 

 of Ammonites to one another ; but we may mention that 

 the author fully adopts the modern views, such as the 

 evolution of the keeled A?naltheus of the Jurassic from 

 Ptychites of the Trias, and also tha t the uncoiled forms 

 {Hamites, Scaphites, &c.) have had several distinct points 

 of origin from true Ammonites. And here we may take 

 the opportunity of mentioning that the terms JF.goceras 

 and Haploceras applied to genera of Ammonites, are 

 preoccupied by two well-known genera of Mammals, and 

 therefore require changing. In regard to the Dibranchiate 

 Cephalopods, it is considered that Belemnites have been 

 derived from forms allied to Goniatites, and have them- 

 selves given origin to the modern Cuttle-fish. If this be 

 the true phylogeny of the Cephalopods, it indicates a 

 gradual increase in the complexity of the shell of the 

 Tetrabranchiates, till it attained its maximum in the 

 Jurassic and Cretaceous. Then the total disappearance 

 NO. I 133, VOL. 44] 



of all the external-shelled forms with the exception of the 

 Nautilus J while at the same time the Dibranchiates 

 were gradually tending to develop less and less complex 

 internal shells, till these culminated in the simple "pens" 

 and "bones" of the modern cuttles and squids. 



Coming to that portion of the work devoted to the 

 Vertebrates, we find, as already mentioned, that the 

 author has been in some places less successful than in 

 the earlier chapters. We have already alluded to the 

 misleading nature of one of the figures in the chapter on 

 fishes, and we have to add that several of the few others 

 with which that chapter is illustrated are highly unsatis- 

 factory. It is probable, indeed, that the author had no 

 opportunity of seeing the second volume of the " British 

 Museum Catalogue of Fossil Fishes " before passing his 

 proofs, as otherwise he would doubtless have modified 

 some of his statements. 



In his remarks on the difficulty of distinguishing be- 

 tween Dipnoid and Ganoid fishes (p. 265), the author 

 seems to be totally unaware of the difference between 

 the " autostylic " skulls of the former and the " hyostylic " 

 of the latter ; and when, on p. 267, he states that the Dip- 

 noids are a lateral branch of the Crossopterygian Ganoids, 

 he is directly at issue with the writer of the Museum 

 Catalogue, who states (p. xx.) that, " concerning the 

 evolution of the Dipnoi, palaeontology as yet affords no 

 information." Again, although Prof. Cope's observations 

 as to the primitive structure of Pteraspis and its allies 

 are referred to, we doubt whether the suggestion that the 

 opening on the dorsal side of the head-shield corresponds 

 to the aperture of a parietal eye will commend itself to 

 the students of ichthyology. The chapter on the Batra- 

 chians is all too short ; and, bearing in mind their resem- 

 blance to the Dipnoids in the autostylic structure of the 

 skull, it is scarcely safe to make the statement (p. 282) 

 that they are derived directly from Ganoids. 



From his treatment of reptiles we fear that the author 

 has but a very faint conception of the nature of a Therio- 

 dont or a Dicynodont, or else he would surely have 

 made more of their affinity to the Batrachians on the one 

 hand, and to Mammals on the other ; while he would 

 have also omitted any reference to the purely adaptive 

 resemblance existing between the skull of Udenodou and 

 that of a turtle. M. Priem might also have informed his 

 readers that Dicynodonts are not confined to Africa. On 

 the other hand, we are pleased to see that M. Priem re- 

 jects the heresy propounded by some of his countrymen, 

 that Ichthyosaurs were derived primitively from marine 

 reptiles, in favour of the more rational view of their near 

 relationship to the Rhynchocephalians. In stating that 

 the Plesiosaurs are likewise related to the Rhyncho- 

 cephalians, the author is in accord with modern views, 

 although he should also have referred to the many in- 

 dications of affinity presented by these reptiles to the 

 Chelonians. When, however, it is stated, on pp. 295, 296, 

 that the latter were probably derived from the toothless 

 Dicynodonts ( Udenodon), the author at once proclaims 

 his ignorance of some of the leading features of reptilian 

 osteology. The statement on p. 297, that the gigantic 

 Siwalik tortoise had a shell measuring four metres in 

 length, leads us to wonder when this fiction will finally 

 disappear from text-books. The author's treatment of 



