346 Mr. G. A. Boulenger on the Chelonian 



thick and leathery on the back. Brown (coloration badly 

 preserved) ; groin and sides of hind limb yellowish, with a 

 wide-meshed blackish network. 



From snout to vent 75 millim. 



A single female specimen. Milne Gulf. 



Named in honour of the Marquis Giacomo Doria, who has 

 so largely contributed to our knowledge of Papuasian 

 herpetology. 



XLIII. — On the Characters of the Chelonian Families Pelo- 

 raedusidse and Chelydida3. By G. A. Boulenger. 



Theee is probably not in the whole classification of Reptiles 

 a more natural division than that of the typical Chelonians 

 {i. e. excluding the Athecee and Trionychoidea) into Crypto- 

 dira and Pleurodira. In addition to the two well-known 

 characters, viz. the lateral bending of the neck and the 

 anchylosis of the pelvis, the latter group differs in the 

 following points : — 



The mandible articulates with the skull by a condyle 

 fitting into a concavity of the quadrate ; the outer border 

 of the tympanic cavity is completely encircled by the 

 quadrate ; the pterygoids are extremely broad throughout and 

 form wing-like lateral expansions ; the cervical vertebrae 

 have strong transverse processes, and their cup-and-ball 

 articulations are single throughout. 



The existing Pleurodira may be divided into three 

 families: — 1. Pelomedusidte ( = Pelomedusidas + Peltocepha- 

 lidge, Gray) J 2. Chelydidaj ( = Chelydid£e + Hydraspidida3, 

 Gray) ; 3. Carettochelydidse *. The latter family, character- 

 ized by the absence of dermal shields on the shell and the 

 paddle-shaped limbs, is at present known from external cha- 

 racters only, but is apparently closely related to the Chelydidas. 

 Considering how widely the first two families differ, it is 

 surprising that their recognition should have been delayed 



* [I have asked Mr. Boulenger, who for some time past has been en- 

 gaged in the study and arrangement of Chelonians, to publish this note 

 in the ' Annals,' in order to preclude any misappi-eheusion as to the 

 authorship of this division of the Pleurodira. This division has been 

 adopted in the article " Tortoise " of the ' Encyclopaedia Britannica,' 

 which bears the signature A. C. G. usually affixed by the publishers to 

 my articles, but which, in fact, is the joint production of Mr. Boulenger 

 and myself. More especially he supplied me in manuscript with the 

 systematic synopsis as inserted in the article. — A. Guntheb.J 



