284 NOTES ON THE PEIIMIAN SYSTEM OE 



PTEROPODA. 



36. THECA ? Morris. 



1, T? KiRKBYi, n. s. PL XL fig. 27, i-estored. 



Shell straight^ taperinc) gradually ; aperture transversely oval ; 

 surface ivith small, transverse, ivavy furroivs ; four thin decurrent 

 wings run along the whole length of the shell. 



This is the only Pteropod that I am acquainted with in the 

 English Permians. The restored outline in the accomx^anying 

 plate will serve to give an idea of its form and size. I have 

 found only one specimen which shows the above characters, and 

 which indicates probably a closer alliance with the Creseis, Bang, 

 than with the genus in which it is provisionally placed. 



It is dedicated, with great respect, to Mr. James Kirkby, of 

 Sunderland. 



From the shell-limestone of Tunstall. 



37. PINNA, Lbui. 

 1. P? PRISCA, Miui* 



Solen? pmnceformis, Geinitz, Ve7'st. p. 8. 



Within the last few weeks, Mr. Kirkby has found an interest- 

 ing specimen of this rare species in the shell-limestone of Tun- 

 stall Hill. Last year I had an opportunity of examining a fine 

 series of s|)ecimens, collected in the neighbourhood of Gera, by 

 Mr. Dinger, Mr. Robt. Eisel, and the Pastor Macroth. Mr. 

 Dinger having kindly presented a fine siDecimen to me, and hav- 

 ing also secured another smaller example from the Zechstein 

 quarries, in the neighbourhood of Gera, I am able to state, with 

 great certainty, the identity of Mr. Kirkby 's fossil with the above 

 Avell-authenticated species. 



In the "Perm. Mon.," p. 4, Mr. King refers the Pinna? prisca, 

 Mlinst., to the Caulerpa selaginoides, Sternb., and remarks that 

 " it is difficult to conceive the figure, in Count Mlinster's '■ Beit- 

 rage,' to be any thing else but the stem of this plant.'' The 



* "Beitr. T.," 1839, p. 45, U. 4, f. 4; 1843, p. 66, H. 4. f. 4. 



