522 Reviews — Dolte's Eocene Chelonians. 



The proposed classification is as follows : 



Order Chelonia. 

 Suborder 1. Prochelonia. — Sect. Macelognatha. 

 2. Euchelonia. — ,, 1. Athecje. 



„ 2. Thecophora. 



Subsect. 1. Pleurodiba. 



2. Cryptodira. a. Dactyloplastra, 

 b. Clidoplastra 

 C. Lysoplastra. 



The first suborder is a purely hypothetical one, and is formed for 

 the ancestors of the known forms which are presumed to have been 

 furnished with teeth. Apart from the general question whether 

 it is advisable to overload scientific nomenclature with terms for 

 hypothetical groups, it appears to us that in this instance the author 

 would have exercised greater discretion if he had refrained from 

 proposing this suborder, since, as Prof. A. Newton has recently 

 shown in the case of the Birds, it does not necessarily follow that the 

 possession of teeth by the more primitive forms of a group entails 

 the separation of such forms from the more specialized groups which 

 have lost these organs. 



The Euchelonia comprehends all known members of the order ; 

 the section Athecse being formed for Sphargis and its fossil allies ; 

 while the section Thecophora includes all other known forms. The 

 first subsection (Pleurodira) of the latter embraces the existing 

 family Chelydidcs and certain Mesozoic forms such as Plesioclielys. 

 The existing members (e.g. Chelys, JPlatemys, and Hydraspis) of this 

 subsection, which is characterized by certain features of the pelvis, 

 and the presence of an intergular plate, are now entirely confined to 

 the Southern Hemisphere ; and it is interesting to note that while 

 JPlatemys is represented in the Lower Eocene of England, a member 

 (H. Leithi) of the South American genus Hydraspis has been described 

 by Dr. Gray from the Eocene of Bombay. In the Cryptodira, which 

 may be now regarded as the Chelonians of the Northern Hemisphere, 

 are included all the remaining members of the order. In the first 

 (Dactyloplastra) of the three groups into which this subsection is 

 divided, M. Dollo recognizes four families, — the Chelonidee, JPropleur- 

 idce, Trioiiychidcs, and Chelydridce. The second group (Clidoplastra) 

 is divided into the Pleurosternidce, Baenidce, Adocidce, Emydidce, 

 Cinosternidm, and Testudinidce ; while the third (Lysosterna) com- 

 prises only the Cistudinidce (e.g. Cistudo, Terrapene, etc.). 



We are by no means sure whether such a complicated division of 

 the Cryptodira is advisable, especially as some English systematists 

 (e.g. Dr. Sclater 1 ) include the Cistudinidce, Cinostemidce, Chelydridce 

 (e.g. Clielydra and Macrochelys or Macroclemmys), and apparently 

 the Baenidai (i.e. if Dermatemys be classed in the latter) in the 

 Emydidce, and do not consider the characters on which M. Dollo 

 relies as of more than generic value. This is, however, a matter on 

 which every scientist who has studied the group is entitled to use 

 his own opinion. 



Turning now to the new forms described by M. Dollo, perhaps 



1 See " List of Animals in Gardens of Zool. Soc." 8th ed. pp. 561-571 (1883). 



