17 



March 11, 1834. 



William Spence, Esq., in the Chair. 



Specimens and drawings were exhibited of a freshwater Tortoise, 

 forming part of the collection of Mr. Bell, by whom it was described 

 as the type of a new genus, for which he proposed the name of 



Cyclemys. 

 Sternum latum, testani dorsalem longitudine fere sequans, inte- 

 grum, solidum ; testae dorsali ligamento squamato connexum. 



Cyclemys orbiculata. Cycl. iestd suborbiculari, carinatd, postici 

 dentatu, fused ; scuds sternijiuvescentibus, fusco radicUim lineatis. 



Long, dorsi, 8 unc. ; lat. 7 ; alt. 3. 



Emys orbiculata. Bell. 



Pullus. Emys Dhor, Gray, Syn. Kept., p. 20.? 



Hab. in India. 



Mr. Bell regards the Tortoise which he has thus characterized as 

 supplying a link in the connecting series of the laud with the fresh- 

 water families which has hitherto been wanting ; and as especially 

 valuable in the natural arrangement, by the clue which it furnishes 

 to the correct location of the Indian forms of the genus Emys. It is, 

 indeed, most nearly related to Emys spinosa, and on a superficial ob- 

 servation might almost be referred to that species ; but on closer 

 examination it is found to differ from that Tortoise, not only specifi- 

 cally, but generically also : its sternal bones are permanently sepa- 

 rated from the dorsal ones, with which they are connected by means 

 of a ligament alone, similar to that which performs the same office in 

 Terrapene. From the Box- Tortoises, however, co which, in this point 

 of its structure, it is so closely related, Cyclemys is altogether distinct, 

 the whole of its sternum being entire, instead of having, as is invari- 

 ably the case in Terrapene, one or more transverse divisions of the 

 sternum itself, the lobes of which move as on a hinge. In Terr. 

 Europcea this mobility of the sternum exists in each lobe in a small 

 degree, combined with the ligamentous connexion of the sternal to 

 the dorsal bones. In Cyclemys the whole sternum moves together, 

 though very slightly. 



The transition from the land to the Jreshwater Tortoises may con- 

 sequently be regarded as commencing in Terrapene ; passing through 

 Terr. Europcea to Cyclemys orbiculata ; and thence through the In- 

 dian forms of Emys, which so closely resemble the latter species, to 

 the other forms of Emys : the natural series of conne.xion between the 

 TestudinidoE and the Emydidce being thus completed. 



The exhibition was resumed of the new species of Shells contained 

 in the collection of Mr. Cuming. Those now exhibited were accom- 



No. XV. Proceedings of the Zoological Society. 



