R. LydeMer and G. A. Boulenger — Notes on Chelonia. 275 



to whicli Prof. Eiitimeyer ^ has already pointed out that the specimen 

 figured by the same writers ^ under the name of Emys Icevis is merely 

 the young of the former, and that owing to the presence of a small 

 mesoplastral bone the reference to Platemys is incorrect, and it is 

 suggested that the species may probably belong either to Podocnemis 

 ■or Peltocephahis. The type is unfortunately not in the collection of 

 the Museum, but the figure shows that the length of the bony union 

 between the carapace and plastron is comparatively long, from which 

 its affinity appears to be rather with the former than the latter, and 

 it may accordingly be provisionally referred to that genus. 



With regard to the large Chelonian figured by Owen ^ under the 

 name of Emys Conyheari, which appears specifically identical with 

 the younger specimen figured as Emys DelabecJii, Bell,* Professor 

 Eiitimeyer^ has observed that it is difficult to say whether these 

 forms belong to the Emydidce or the Cliehjdidce, but this difficulty has 

 now been decisively solved. The best preserved and larger of the 

 two specimens, or that figured under the name of E. Conyheari, 

 shows both carapace and plastron, and exhibits in the latter distinct 

 mesoplastral bones like those o^ Podocnemis. The matrix between the 

 carapace and plastron has recently been chiselled away, and the 

 characteristic Pleurodiran anchylosis of the ischium and pubis to 

 the plastron is thus exhibited. In the number of the neural (verte- 

 bral) bones, in the flatness and general contour of the carapace, in 

 the shape of the plastron and the relative length of the bridge 

 uniting the latter with the carapace, and in the absence of a nuchal 

 epidermal shield, the specimen accords so well with Podocnemis, that 

 it may be pretty safely referred to that genus, under the name of 

 P. DelahecM. The jDresence of two epidermal pygal shields diff'er- 

 entiates it from the allied genus Peltocephahis ; the vertebral shields 

 agree in form very closely with those of Podocnemis Dumeriliana, 

 although the contour of the carapace accords more closely with that 

 of P. expansa. With regard to the so-called Emys hicarinata ® from 

 the same formation, a cutting-away of the matrix shows no trace of 

 the pelvis, which was probably, therefore, of the Cryptodiran type, 

 and the sjDCcies may accordingly, in the absence of any evidence to 

 the contrary, be included in the genus Clemmys. The occurrence of 

 Podocnemis in the London Clay indicates that the Pleurodira, which 

 are now almost entirely relegated to the Southern Hemisphere, were 

 dominant forms at that period in the European area, as they also 

 were in the corresponding epoch in India, where there were repre- 

 sentatives of both Podocnemis and Platemys in the Lower Eocene.'' 



1 Verh. Nat. Ges. Basel, p. 121. 



2 Op. cit. pi. xxii. 



' Eeptilia of Loudon Clay, Supplement, pis. xxviii. A, B. 

 * Ibid. pi. xxviii. 



5 Verb. Nat. Ges. Basle, oj». cit. p. 121. 



^ Owen and Bell, Eeptilia of the Loudon Clay, pt. i. pis. xxv. xxvi. 

 ■^ These species will be described in a forthcoming memoir in the '* Palaeontologia 

 Indica," ser. 10, vol, iv. pt. 3.— [R. L.] 



