146 CHELONIA. 



agrees with that of Macrochmmys are as follows, viz. : — 

 the markedly triangular form and the great width across 

 the tympanic region, the roofing over of the temporal 

 fossa, the apparent similarity in the contour of the occipital 

 surface and of the tympanic ring, the identity in the 

 general plan of structure of the lateral portion of the 

 palate and of the postorbital septum. The character of 

 the latter septum indicates decisively the Cryptodiran 

 affinities of this skull. 



BowerbanJc Collection. Purchased, 1865. 



40099. The imperfect posterior extremity of the shell ; from Sheppey. 

 Noticed by G. A. Boulenger and the writer in the ' Geol. 

 Mag.' dec. iii. vol. iv. p. 274, where it is referred to 

 the present species. This specimen shows no characters 

 by which it can be specifically distinguished from the 

 type carapace figured by Dollo in the ' Bull. Mus. R. Hist. 

 Nat. Belg.' vol. iv. pi. i. It exhibits the seventh neural, 

 which is of very small size, the imperfect seventh and 

 the entire eighth costals, and the supra-pygal. The 

 eighth costals meet in the middle line. Some fragments 

 of costals are shown on the inferior aspect of the speci- 

 men. Purchased, 1866. 



38965. A pygal bone ; from Sheppey. This specimen agrees well 



with the contour of the corresponding bone (marginal of 

 Dollo) in the type ; its length being 0,072 (2-85 inches), 

 and its distal diameter 0,670 (2*65 inches). It is relatively 

 larger than the pygal of the type species of Anostira, but 

 exhibits the same sudden thickening at the commencement 

 of the free portion, and a similar dorsal ridge. In the 

 type specimen these features are lost by crushing. 



Bowerbank Collection. 



38966. A smaller pygal, imperfect distally ; from Sheppey. 



Boiverbank Collection. 



The following specimens may perhaps belong to this form. 



37217. Fragment of a bone which is apparently a portion of a nuchal; 

 probably from the London Clay of Sheppey. There is a 

 pair of mesial prominences apparently corresponding to 

 those mentioned by Leidy as occurring in the nuchal of 

 Anostira. Purchased, 1860. 



