62 CHEL0NIA. 



carapace is represented by the anterior neurals, many of 

 the left costal*, some of the marginals, and a cast of the 

 inner aspect of much of the other portions. In the thick 

 ribs and narrow costals, as well as in the contour of the 

 neurals, it agrees with the type specimen (infra). The 

 vacuities between the costals and marginals are reduced 

 to even a smaller size than in specimens of Thalassochelys 

 of the same size. Noticed by the writer, op. cit. p. 65. 



No history. 



38954. The imperfect cranium of a young individual; from the 

 London Clay of the Isle of Sheppey. This specimen, 

 which, as noticed by the writer, op. cit. p. 66, lacks the 

 extremity of the muzzle and part of the parieto-occipital 

 region, is indistinguishable in contour from the cranium 

 of the preceding specimen. It also resembles in many 

 respects the type cranium of L. longiceps, having the same 

 arrangement of the shields ; but it differs in the wider 

 inferior apertures of the temporal fossae, and in the much 

 shorter interval between the orbits and nares. The 

 relatively large size of the orbits indicates immaturity. 

 The posterior nares, instead of being placed close to the 

 occiput, as in the adult skull, are situated slightly in 

 advance of the anterior border of the temporal fossae. It 

 would, however, merely require the backward growth of 

 the vomer and palatines to produce the same condition 

 as obtains in the adult. There are analogous changes in 

 the position of the posterior nares in Thalassochelys 

 caretta, according to the age of the individuals. 



Bowerbank Collection. Purchased, 1865. 



R. 1475. A more imperfect cranium agreeing in size with the 

 preceding specimen ; from Sheppey. The posterior part 

 of the palate is well shown ; the posterior nares are 

 somewhat further back than in the preceding specimen. 



No history. 



R. 912. Two portions of a split nodule showing the imperfect inner 

 (Fig.) surface of the carapace of a half-grown individual, and 

 the counterpart of the same ; from Harwich. The type 

 specimen. Figured by Owen in his ' llcptilia of the London 

 Clay, &c.' vol. i. pt. i. pi. xii. The impressions of the 

 anterior neural bones are distinct. No hiatory. 



