146 Dr. J. E. Gray on Tortoises. 



Vertebral plates keeled, more especially the three hinder ones. 

 Above black ; under margin and sternum white, with a large 

 black blotch occupying the greater part of the middle of each 

 sternal shield. Sternum flat, rather convex, greatly bent up 

 in front. Shell 1\ inches long, 5^ inches wide. 



Hah. Tropical America (Mus. Utrecht, no. 39). 



This shell was at one time taken for a specimen of IlardeUa 

 Thurgi] but it is very unlike, and is at once known from that 

 genus by the peculiar triangular form of the first pair of mai-- 

 ginal plates, as in the other species of this genus. The dorsal 

 and side of marginal plates have a more or less dark spot in 

 the centre of the areola. 



Emys Fraserij n. sp. 



Shell olive, minutely darker-spotted; underneath darker, 

 black-varied. Front legs with a series of four or five large 

 plates on the outer edge, and with two larger plates on the upper 

 part of the outer side of the front legs. Jaws strong, with a 

 rather broad alveolar surface. 



Hob. Lake Tetzara, Algiers. Shell 8 inches long. 



This species has much the appearance of Eryma laticeps, 

 with which it has been confounded ; but the head is much 

 longer, and the alveolar surface of the two jaws narrower. It 

 agrees with Emys caspica in the shape and proportions of its 

 head ; but the alveolar surface of the jaws is much wider. 



I do not know if Emys caspica is also found in Algiers ; but 

 we have in the British Museum four very young Terrapins 

 {one brought by E. Doubleday, one by Canon Tristram, and 

 two by Mr. Eraser) from that country, which have a red stripe on 

 each costal plate, and a black sternum, like the young Emys 

 caspica. Perhaps this character is common to the young of 

 the two species. One of these I have called Emys Eraser i in the 

 'Suppl. Cat. Shield Rept.' p. 36. 



Chrysemys. 

 We have in the museum three distinct forms of this genus, 

 which in a large series do not appear to pass into each other, 

 and which have special localities. 



1. Chrysemys picta. 



Sternum one-coloured, pale edge of the front discal plate 

 broad ; lateral angles of the second, third, and fourth vertebral 

 plates anterior ; marginal plates with a central spot and con- 

 centric rings above, and a yellow spot beneath. 



Hah. North America, Eastern States. 



