PLESIOCHELYID^. 183 



46375. An imperfect posterior marginal; from the Cambridge 

 Greensand. The sulcus between two marginal shields is 

 distinctly visible. 



Cunnington Collection. Purchased, 1875. 



35188. A smaller free marginal ; from the Cambridge Greensand. 



Purchased, 1859. 



35188 a. Fragment of a posterior marginal, not improbably asso- 

 ciated with the preceding ; from the Cambridge Green- 

 sand. Purchased, 1859. 



35188b. An imperfect costal; from the Cambridge Greensand. 

 This specimen may have been associated with the last. 



Purchased, 1859. 



43981. Fragment of a costal ; from the Cambridge Greensand. In 

 this specimen the pustulation is much finer than in the 

 preceding ; a difference which is probably specific. 



Purchased, 1872. 



Family PLESIOCHELYIM] \ 



Shell usually thick, without mesoplastrals, and with either a 

 reduced or the full number of neurals and suprapygals ; only the 

 pubis uniting with the xiphiplastral. Entoplastral small. Infra- 

 marginal shields at least usually present. Skull (when known) 

 with roofed temporal fossae ; other characters not definitely known. 

 Phalangeals of manus, when known (Idiochelys and Parachelys), 

 reduced in number. There may be a plastral vacuity. 



The skull is definitely known in Idiochelys. In a skull from the 

 Kimeridgian of Hanover, figured by Portis in the ' Palseonto- 

 graphica,' vol xxv. art. 3, pi. xvii. figs. 12, 13, and said to have 

 been associated with the carapace and plastron of the so-called 

 Chelonides wittei (vide infra, p. 197), the temporal fosssG are roofed, 

 and the palatines are described as meeting in the middle line. The 

 skull which Kutimeyer suggests may be referable to Plesiochelys is 

 noticed below (p. 204) ; its temporal fossae are roofed over, the 

 palatines are in contact, there are said to be no distinct nasals, and 

 the pterygoids are of a Cryptodiran type. 



1 Usually given as Tledoehclydida?. 



