CHELONmE. 31 



at the posterior border of the oral surface. Carapace long and 

 narrow, with deeply emarginate nuchal ; neurals comparatively short 

 and wide, with the antero- and postero -lateral surfaces of subequal 

 length, and with a strong keel ; costals long antero -posteriorly, and 

 extending only a short distance down the ribs, which are slender 

 and sharply denned ; marginals long, and the posterior ones with 

 the free border entire. In consequence of the form of the neurals 

 the intercostal sutures join the middle of the sides of the neurals. 



The contour of the mandibular symphysis approximates to that 

 obtaining in Argillochelys, but the pterygoids, as figured by Winkler 

 (' Tortues Fossiles,' pi. ix.), are of the type of those of Chelone. 

 The bones figured by Winkler, op. cit. pi. x., as the coracoid belong 

 to the pelvic girdle. There is no evidence to show that the frag- 

 ments from the English Chalk referred provisionally by Owen to 

 this species are rightly named. A fine example of the cranium is 

 figured by Ubaghs in the ' Bull. Soc. Belg. Geol.' vol. ii. pis. x.-xiii. 



Hah. Europe (Holland). 



The following specimens were obtained from the Uppermost Cretaceous 

 of Maastricht, Holland; and, unless the contrary is stated, 

 belong to the Van Breda Collection. Purchased, 1871. 



42913. Slab showing the anterior and left lateral aspect of the 

 imperfect skull, a large portion of the marginal region of 

 the carapace, and portions of the plastron and pelvis. 

 The general contour of the cranium resembles that of 

 C. imbricata. 



42889. Slab showing the oral aspect of the imperfect mandible. 

 (Fig.) Figured by Winkler in his ' Tortues Eossiles conservees 



dans le Musee Teyler, etc' (Haarlem, 1869), pi. xiv. figs. 

 46, 47. The symphysis is damaged, but its relative 

 shortness is well shown. 



42890. The mandible, imperfect posteriorly. The symphysis has 



been somewhat waterworn, but exhibits its characteristic 

 features. 



42891. The symphysial region of the mandible, with the oral sur- 



face concealed by matrix. 



42892. The imperfect symphysis of the mandible. As in the pre- 



ceding specimens, the summits of the alveolar walls have 

 been worn away. 



