MR. E, LYDEKKEK OX A NEW SPECIES OF TRIOXYX. 37 



3. On a jSTew Species of Tuioi^YX from the Miocene of Malta anc? 

 a Chelonian Scapula /rom the London Clay. By R. Lydekker, 

 Esq., B.A., F.G.S. (Read iS'ovember 12, 1890.) 



I. Teionyx from Malta. 



In a paper read before the Society in N'ovember, 1885, I described 

 part of a Crocodilian skull from the Miocene of the Maltese Islands, 

 which was referred to the existing Oriental genus Tomistoma * ; 

 attention being at the time particularly directed to the interest of 

 the occurrence, in those deposits, of a genus now confined to one 

 island in the purely tropical Malay Subregion of the Oriental Region. 

 On the present occasion I bring to the notice of the Society evi- 

 dence of Oriental affinities in a member of the Chelonian family 

 Trionychidce, of which the remains have been recently obtained from 

 the Miocene of Malta. 



The specimen forming the subject of this part of the paper is one 

 of a small collection brought from Malta by Dr. John Murray, and 

 presented by him to the British (I^atural History) Museum. It con- 

 sists of a portion of the middle and right half of the anterior region 

 of the carapace of a large Chelonian referable to the family Triony- 

 chidce. The specimen, of which a reduced and restored representa- 

 tion is given in the accompanying figure, is embedded in the 

 characteristic buii limestone of Malta, with the sculptured surface 

 exposed. The nuchal bone (nu) is missing, but the greater part 

 of the first four costals (c^-o^ ) of the right side are preserved ; 

 and there also remain portions of five neural bones, and the inner 

 extremities of the first, second, and third costals of the left side. 

 The form of the neural {n^) situated between the third costals, 

 with its shorter lateral surfaces placed posteriorly, is alone sufficient 

 to show that the specimen belongs to the anterior half of the 

 carapace. The forward inclination of the fourth costal is, however, 

 ap]Darently due to the flattening which the specimen has undergone. 



The carapace indica,tes a species nearly or quite as large as the 

 existing Chitra indica, the length of the third neural being 2'8 inches. 

 It also agrees with that species in the coarseness of the sculpture, 

 but this feature is also met with in some species of Trionyx. The 

 comparative shortness of the ribs and costal plates suggests that 

 the specimen is not fully adult. 



Before proceeding further, it should be observed that the three 

 Indian species of Triony.v {\\z, T.gangeticiis, T. Leithi, and T. Imriim) 

 differ from all other members of the family in having two neural 

 bones between the first pair of costals t, this being apparently due 

 to a subdivision of the normal first costal. All the fossil species 

 hitherto described, of which the entire carapace is known, agree 



* See Quart. Journ. Geol. See. vol. xlii. p. 20 (1886). 



t See Boulenger/Catc-Jogue of Chelonians, &c. in Brit. Mus.' p. 244 (1889). 



