TKSTllUNJD.i:. 49 



]iages, so far as consistent with Avliat apjiear to be the aft'nities of 

 tlie various forms. 15iit for the necessities of a serial aminjrenient, 

 tlio genus Einiji; in many respects the least specialized, might be 

 l)laced at the base of the family, ^vith two diverging series of genera 

 culminating in the Batagurs on the one hand and in tlie J.and- 

 Toitoises on the other. 



Si/noj),s-is of the Genera. 



I. Digits usually webbed, or with at least a slight rudiment of 

 web, the median with three phalanges ; metacarpals elongate. 



A. Hexagonal neural plates short-sided in front. 



]. Alveolar surface of upper jaw broad, with one or two 

 median ridges. 



a. Axillary and inguinal buttresses much developed, the 

 former connected with or nearly reacliing the fiist rib, 

 the latter anchylosed between two costal plates (5th 

 and Gth) ; cntoplastron anterior to the humero-pectoral 

 suture. 



a. Fourth vertebral shield elongate, embracing four or 

 five neural bones . . 1. Kachuga, p. 51. 



ft. Fourth vertebral shield not longer than third, (nibra- 

 cing three neural bones. 



Choarse between the eyes ; alveolar surf;:ce of upjier jaw with a 

 single median ridge ". 2. Callagur, p. GU. 



Choana* behind the level of the eyes : alveolar suri'ace of upper jaw 

 with two median ridges ; fore limb Avith lour claws only. 



3. Batagur, p. Gl. 



Choanse behind the level of the eyes ; alveolar surface of upper jaw 

 with a single mediau ridge .... 4. Hardella, p. G3. 



6. Axillary and inguinal buttresses short or moderate, 



Choanse behind the level of the eyes; inguinal buttress anchy- 

 losed to the fifth (exceptionally sixth) costal plate ; entoplastron 

 anterior to the humero-pectoral suture. 



5. Morenia, p. G6. 



Choana; between the eyes ; inguinal buttress anchylosed to the fifth 

 costal plate ; entoplastron anterior to the humero-pectoral suture. 



6. Chrysemys, p. 69. 



Choana? between the eyes ; inguinal buttress anchylosed between 

 the fifth and sixth costal plates; enloplastron intersected by the 

 humero-p.ectoral suture 7. Ocadia, p. b5. 



