36 PEOCEEDINGS OF THE GEOIOGICAL SOCIETY. 



face smooth. Beak moderately produced, and truncated by a small 

 foraminal aperture ; marginal line slightly curved in front, but not 

 affecting the regular convexity of the dorsal valve, while it produces 

 a small depression or sinus near the front of the ventral. Only one 

 specimen of this shell was found by Capt. Godwin- Austen in Thibet ; 

 it measures 1 inch in length and breadth, by ^ inch in depth. 



2. Spieieee, sp. PI. I. fig. 4. 



Of this Spirifer, two fragments of the dorsal valve have been col- 

 lected ; when perfect it was semicircular, moderately convex, with a 

 smooth wide slightly raised mesial fold, each valve being orna- 

 mented by some twenty-eight or thirty flattened ribs. The ventral 

 valve being unknown, it would be unsafe to venture upon a specific de- 

 termination, especially as several Devonian and Carboniferous species 

 present characters very similar to those displayed by the fragment 

 under description. 



3. B,HT]srcHoifELLA PLEUEODON, var. Daveetjxian^a, De Koninck. 



PI. I. figs. 2 & 3. 



Several specimens agreeing with British and Belgian examples 

 of R. Davreuociana, De Koninck, have been found by Capt. Godwin - 

 Austen (see Davidson, ^ Mon. British Carb. Brachiopoda,' pi. 23. 

 figs. 19-21). 



4. Oethis, sp. PI. I. fig. 5. 



Two fragments of one valve only were collected by Capt. Godwin- 

 Austen. In shape this valve is semicircular, with rounded cardinal 

 angles, 1 inch in length, by 1 inch 2 lines in breadth. It is mode- 

 rately convex and ornamented bynumerous fine radiating stria3, which 

 increase in number by the interpolation of ribs at various distances 

 from the beak. The surface is likewise crossed by numerous con- 

 centric lines. These fragments are not, however, sufiiciently com- 

 plete to warrant a specific determination. 



5. Peoductus semieeticulattjs, Martin. PI. I. fig. 6. 



Specimens of this characteristic Carboniferous shell do not appear 

 rare in the Thibet limestone. 



6. Chonetes Haedeensis, var. Thibetensis. PL I. fig. 7. 



This smaU species occurs by millions in the Carboniferous lime- 

 stone and shale of Thibet, where it does not appear to have 

 much exceeded 4| hues in length and 7 in width. Prof. De Ko- 

 ninck agrees with me in considering it to be a variety of G. 

 Hardrensis. The shell is semicircular, concavo-convex, with a 

 straight hinge -line, each valve being provided with a narrow sub- 

 parallel area. The surface of each valve is ornamented with from 

 thirty-five to fifty rounded ribs, of which a small proportion are 

 due to interpolation. The surface is also traversed by fine con- 

 tiguous striae. As I have elsewhere observed, G. Hardrensis is a 

 very variable species, and this has, no doubt, induced palaeontolo- 



