172 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jail. 7, 



Hemithyris Tonga, M'Coy, British Pal. Foss. p. 440, pi. 3. D. fig. 24, 

 1855. 



Of this very small shell I have been able to examine only three 

 specimens ; but it is stated to be abundant in a yellow arenaceous 

 limestone at De Bert Biver, where, according to Dr. Dawson's ex- 

 perience, it is always small. I have also felt somewhat puzzled 

 in the determination of this fossil ; but, after having consulted Prof, 

 de Koninck, I concluded to refer the specimens represented in figures 

 11 and 12 to the same species, notwithstanding the apparent difference 

 they present. Prof, de Koninck referred fig. 12 to T. rliomboidea, 

 Phillips, which is a synonym of Camarophoria globulina ; and, after 

 minutely comparing the Xova-Scotian specimens with the Carboni- 

 ferous and Permian types, I could perceive no difference sufficient to 

 warrant the creation of a new species. The three specimens were 

 exactly of the same size, namely 3 lines in length by 3 in width and 

 2 \ in depth. The uncertainty which both Prof, de Koninck and 

 myself have experienced refers to fig. 11, which much resembles, in 

 miniature, a form of Mhynchonella acuminata ; but when we remember 

 that Phillips himself figures a specimen of his Terebratula rliomhoidea 

 with a simple mesial fold, we need not be surprised to find the same 

 peculiarity in one of those from Nova Scotia. Indeed, after carefully 

 examining the three examples forwarded by Dr. Dawson, I cannot 

 bring myself to believe that they should be specifically separated. It 

 is well known that the same peculiarity occurs with Rliynclionella 

 acuminata ; and any one who examines plates 20 and 21 of my Mono- 

 graph of British Carboniferous Brachiopoda must feel surprised at the 

 immense variability of which some species are susceptible. 



7. Bhynchokella Dawsoktana, n. sp. ? PI. IX. figs. 13, 14. 



Shell very small, almost circular, a little wider than long ; dorsal 

 valve moderately and uniformly convex to about half its length from 

 the umbone, at which point a very slightly elevated and flattened 

 mesial fold begins to rise, and extends to the front ; the surface of the 

 shell is also either almost entirely smooth or ornamented with from 

 eight to twelve slightly marked ribs. The ventral valve is gently con- 

 vex, with a wide sinus ; beak small and incurved. Length 3^ lines, 

 width 4 lines, depth 21 lines. 



This small species does not appear to be rare in a black Lower 

 Carboniferous limestone at Lennox Passage, and is not unlike, ex- 

 cept in size, certain examples of M. deVerneuil's Terebratula superstes; 

 but this last-named Permian shell belongs to the genus Camaro- 

 plioria, while the one under description belongs to Rliynclionella. I 

 have compared it with a number of equally small young examples of 

 Rliynclionella pu gnus, from which it appears to differ. 



8. Khynchonella Acadiensis, n. sp. ? PI. IX. fig. 16. 



Shell small, obscurely rhomboidal, about as wide as long ; dorsal 

 valve rather more convex than the ventral, and presenting, when 

 viewed in profile, a regular curve. The mesial fold commences to- 

 wards the middle of the valve, while the surface is ornamented with 



