CHELTDEIDJi. 14U 



R. 1446. !8lab of limestone showing an imperfect costal bone of a 

 small individual; from the Pnrbeck, locality unknown. 



Ao history. 



Subfamily Axostirix.£. 



8hell with venniculated sculpture, and without (or with very thin) 

 epidermal shields ; no persistent vacuity in plastron, which has a 

 moderately long bridge, and a nearly or quite straight suture 

 between the hypo- and xiphiplastrals ; neural bones seven in number, 

 hexagonal, and long or narrow ; typically 10 marginals ; caudal 

 vertebras unknown. 



The writer provisionally follows Cope 1 in including the type genus 

 in the present family, with which it agrees closely in the form of 

 the shell. On account of the presence of only 10 marginal bones, 

 and the reduction in the number of the neurals, Baur 2 has proposed 

 to refer it to the Dermatemydidce (Staurotypidce) or Cinostemidce. 

 The presence of the full number of neurals in Baptemys {Bermat- 

 emydidce) shows, however, that the number of these bones is not of 

 family value ; while in the same family we have Dermatemys with 

 11 and Staurotyjrus with 10 marginals. The Chelydroid character 

 of the skull referred to Pseudotrionycc is in favour of Cope's view. 



Genus ANOSTIRA, Leidy 3 . 



Anterior border of carapace deeply emarginate ; plastron articu- 

 lating with carapace by suture, and bridge without distinct inguinal 

 notch ; suture between hypo- and xiphiplastrals forming an obtuse 

 angle ; dorsal surface of neurals and ventral surface of anterior 

 marginals smooth ; posterior border of carapace serrated ; skull un- 

 known. 



The type species is from the Upper Eocene of North America. 

 Baur 4 states that there are traces of thin epidermal shields on the 

 carapace. 



Anostira anglica, Lydekker 5 . 



Imperfectly known. Of large size, the length of the carapace 

 being approximately four times that of the typical specimen of 

 A. oniata, Leidy, which measures 0,1 20 (4*7 inches). 



Rah. Europe (England). 



1 Yertebrata of the Tertiaries of the West — Eep. TL S. Geol. Surv. Terrs, 

 vol. iii. p. 112 [1884). 



- Aim. Mag. Nat. Hist. ser. 6.. vol. iii. p. 58, note (1689). — On page 276 of 

 same it is suggested that this subfamily should form a distinct family. 



3 Proc. Ac. Nat. Sci. Philad. 1871, p. 102.— Jnosteira. * Loc. cit. 



5 Ami. Mag. Nat. Hist. ser. 6, vol. iii. p. 54 (J8C9). 



