﻿RHYNCHONELLA. 



93 



in being much more tumid in the middle, and in having three or more sharp angular 

 furrows, extending along the middle of the large marginal sinus almost to the beaks, and 

 is very variable in magnitude." A single specimen is represented by the author, and of 

 this I have given four carefully drawn representations (fig. 8). In his ' Synopsis, 5 Professor 

 M'Coy states that " B. cordiformis is chiefly distinguished from one of the varieties of A. 

 acuminata by being more convex or tumid at the sides, and in the length and distinctness 

 of the mesial plaits." Professor de Koninck, on the contrary, believes B. cordiformis, or at 

 least the specimen described as such by Sowerby (fig. 8 of our plate), to be nothing more 

 than a simple variety of Bh. acuminata; and although I am not yet perfectly convinced 

 of the fact, it is very possible that my Belgian friend may be correct in his interpretation. 

 In British collections, however, the shells which we usually designate B. cordiformis, and 

 of which one or two examples so labeled exist in Sowerby's cabinet, are similar to those I 

 have represented by figs. 9 and 10, and which are supposed to belong, rightly or wrongly, 

 to the same species as Sowerby's type. These Professor de Koninck considers quite dis- 

 tinct from either B. acuminata or B. reniformis, since he sends me an Irish specimen 

 marked " nov. sp.," and on the label points out the differences he had observed. 



I must admit that I am still much puzzled how to decide ; for I once even supposed 

 that the last-named shells might, perhaps, constitute a variety of B. reniformis, and that 

 Sowerby himself may have had a similar idea, from the fact that he figures among his 

 specimens of B. reniformis, in tab. ccccxcvi of the ' Mineral Conchology, 5 a specimen 

 very similar to the two I have represented (figs. 9 and 10), but without reference, as if he 

 afterwards doubted the identity. If it should be determined that the typical example of 

 B. cordiformis must be referred to B. acuminata, and that the other two (figs. 9 and 10) 

 are distinct, I think the name Cordiformis might be advantageously retained for these last, 

 as they have been so long known under that designation among British collections. 



Loc. The shells here described are generally found in the Carboniferous limestone, 

 associated with B. reniformis. Mr. Burrow has obtained it at Settle, in Yorkshire, and I 

 have specimens from Bolland. In Ireland Messrs. Kelly and Morris mention Millecent, 

 Little Island, Cork, and Ardconnaught. I am not acquainted with any Scottish specimen, 

 but Professor de Koninck has figured the shell from Belgium. 



Rhynchonella acuminata, Martin (sp). Plate XX, figs. 1 — 13 ; Plate XXI, figs. 1 — 20. 



Conchyliolithus anomites acuminatus, Martin. Petrif. Derbs., pi. xxxii, figs. 7, 8 ; 



and pi. xxxiii, figs. 5, 6, 1809. 

 Terebratula acuminata, Sowerby. Min. Con., tab. cccxxiv, fig. 1, Jan. 1822. 



— — var. sulcata, Sowerby. Ibid., tab. ccccxcv, fig. 3, Sept. 1825. 



— platyloba, Sowerby. Ibid., tab. ccccxcvi, figs. 5, 6, 1825. 



— acuminata, V. Buch. Ueber Terebratula, p. 33, 1834 ; and Mem. Soc. 



Geol. de France, vol. iii, p. 131, pi. xiv, fig. 1, 1838. 



