722 EEPTILIA. 



scales. Head, in life, leaden ; iris brown ; neck and skin of limbs pale yellowish- 

 brown. Large scales on the limbs blackish, with brownish margins. 



Inches. 



Total length of carapace 9*00 



„ of sternum 8-10 



Axillary breadth 5-90 



Inguinal „ 6*70 



Breadth greatest over curve . .8*60 



Depth through skull . . . ' 3' 00 



The only locality from whence I have obtained examples of this interesting 

 species was the hilly region in the neighbourhood of Akyab in Arracan. 



Genus Emys, Cuvier. 



It is being gradually discovered as naturalists look to the structure of the ani- 

 mals which have been referred to the genus Emys, that it includes many forms 

 which cannot be regarded as generically identical. So little, however, is yet known 

 of the structure and real affinities of the animals comprising it, and of their relations 

 to each other, that any attempt to group the animals into genera, based on present 

 knowledge, must be essentially tentative. Dr. Gray, who has contributed much 

 to our knowledge of the Chelonia, in describing the species in the British Mu- 

 seum in 1855, referred 33 species to the genus Emys; but in 1870, after a con- 

 sideration of more ample materials, and chiefly of the skull characters, referred the 

 33 species to no less than 12 distinct genera, some of which are undoubtedly well 

 marked generic types of structure, the features of which are especially pro- 

 nounced in the modifications which take place in the skull, more particularly in the 

 character of the fronto-nasal region, the zygomatic arch, and the alveolar surface 

 of the jaws and palate. Such modifications are generally found extending to a 

 number of species, but the differential features are occasionally masked by similar- 

 ity in the outward form. On the other hand, species which by external appearance 

 would be thought widely apart are found, on close examination and on reference 

 to the internal structure of the shell and skull, to be very closely allied, e. g., the 

 two sub-genera Morenia and Hardella among the Bataguridce. These two sub- 

 genera, however, are placed by Strauch widely apart, Morenia ocellata being grouped 

 next to JPangshura smithi, and Siardella thurgi close to Emys trijuga, with which 

 it has no more affinity than Morenia ocellata has with Fangshura smithi. The 

 forms referred to Emys, by Strauch, also present a remarkable diversity of structure, 

 as is seen in the two species 'Fyxidea mouhotti and Cyclemys orbiculata. Bell, 

 the latter of which possesses cloacal bladders and a broad palate like Geoemyda, 

 whereas Pyxidea mouhotti has no cloacal bladders, and has a narrow palate like 

 Emys, with a feeble zygomatic arch, a character which also occurs in the skuU of 

 Cyclemys, and in some of the North American forms referred to Cistudo. 



Dr. Gray referred^ the Emydidce to three types of structure, the Geoemydina, 

 Emydina, and Belliana, the first typified by the genus Geoemyda, the second by the 



» Suppl. Cat. Shd. Kept., 1870, p. 25. 



