﻿110 



BRITISH CARBONIFEROUS BRACHIOPODA. 



located with Rhjnchonella, whence it may be hereafter removed, should the neces- 

 sity for so doing become apparent. Seven British examples alone have come under my 

 notice, and of these four will be found represented in our plate. Three good specimens 

 from the Carboniferous limestone of Alstonfield, in Derbyshire, may be seen in the 

 Museum of Practical Geology ; while the remaining four, which form part of the Gilbert- 

 sonian Collection in the British Museum, were probably derived from a different locality, 

 as they are more triangular and flattened than the Derbyshire examples above mentioned. 

 Professor De Koninck, who first described and illustrated the species, mentions that it is 

 among the rarer species from the Carboniferous limestone of Vise, in Belgium. 



Doubtful Species. 



# 



A. Rhynchonella (?) nana, M'Coy. PI. XXV, fig. 15. 



Atrypa nana, M'Coxj. Synopsis of the Characters of the Carboniferous Fossils of Ireland, 



p. 155, pi. xxii, fig. 19, 1844. 



" Spec. Char. Orbicular, or slightly ovate, compressed, beak pointed ; surface radiated 

 with about ten straight, equal, obscurely angular ridges, none of which reach the beak. 

 • This little species resembles T. radialis in form, but is much flatter, and has considerably 



fewer, larger, and more angular ribs, all of which disappear before reaching the beak, as 

 in the A. subdentata and rotunda, Sow., from both of which it is distinct by its greater 

 flatness, and more numerous radiating ridges ; it is also much smaller than any of those 

 shells. Length two lines, width two lines." (M'Coy's 'Synopsis,' p. 155.) 



Obs. As all the endeavours I have made to procure the sight of a specimen of this 

 shell have proved unsuccessful, the only thing I can do is to reproduce the author's 

 description and figures. These are not, however, sufficiently detailed or precise to permit 

 of any comment as to the probable generic or specific value of the species ; and it is even 

 possible and probable that A. nana may be but the fry or young of some other of the 

 described species, such as of B. pleurodon (?), of which some young examples of similar 

 dimensions would closely resemble. The species cannot, therefore, be admitted upon 

 such vague and uncertain grounds, and is only here appended for the sake of reference. 



Mr. Kelly informs me that the A. nana is common at Rahoran, in the county of 

 Tyrone, and that it occurs in a Calciferous slate, which is situated between the limestone 

 and a reddish sandstone, which forms the basis of the Carboniferous system in Ireland. 

 It is to be regretted that of a shell stated " so common," not a specimen could be procured 

 for the present monograph. 



