ACICHELTID^]. 157 



45921. The first left costal of a nearly adult carapace ; from the 

 Kimeridge Clay of "Weymouth. The contour of the whole 

 bone, as well as that of the portions of the first and 

 second vertebral shields still remaining, is precisely the 

 same as in the preceding specimen. The relatively large 

 facet for the antero-lateral surface of the first neural at 

 once fixes the generic position of this specimen. The bone 

 is smaller than the first costal of the specimen figured by 

 Riitimeyer, but exhibits the great thickness characteristic 

 of this genus. Purchased, 1874. 



42372. The left hyoplastral of an immature individual belonging 

 either to the present or one of the allied genera : from 

 Weymouth. This specimen closely resembles the hyoplas- 

 tral of the opposite side figured by Riitimeyer, op. cit. pi. 

 ix. fig. 1, and shows the long axillary buttress. 



Purchased, 1870. 



Generically Undetermined Specimens. 



The following specimens of humeri of Mesozoic Chelonians are 

 probably referable to the present family, since they differ from the 

 corresponding bone of the Plesiochelyidai (vide Parachelys), and the 

 Acichelyidce appear to be the common forms in the Kimeridge Clay, 

 from which the majority of the undermentioned specimens were 

 obtained. Moreover, they appear to agree with the humerus of 

 Acichelys (No. 41958). 



44180. A left humerus ; from the Kimeridge Clay of Weymouth, 



(Fig.) Dorsetshire. Figured in woodcut fig. l,A(p. 2). This 



type of bone is characterized by the very imperfect develop. 



ment of the head, and the slight ventral inflection of the 



radial process. Purchased, 1873. 



43033. The proximal part of a nearly similar left humerus; from 

 Weymouth. Larger than the last. Purchased, 1871. 



44180 a. The proximal part of a similar right humerus ; from 

 Weymouth. Purchased, 1873. 



44180b. The proximal half of an apparently similar humerus: 

 from Weymouth. Purchased, 1873. 



45923. The distal portion of a humerus or femur probably belonging 

 to the same group as the preceding specimens ; from 

 Weymouth. Purchased, 1874. 



