ATHYR1S. 17 



Athyris hispida, Sow. (fig. 24), has been considered by Professors M'Coy and Morris to 

 belong to A. eoncentrica ; but not having been able to see the original example, I can 

 hardly express a decided opinion upon the subject. 



M. Bouchard is of opinion that figs. 11 and 12 of our plate should be considered a 

 different, but closely related, species ; but I have not ventured to separate them from 

 A. eoncentrica, to which they appear to me connected by numerous gradations in shape ; 

 indeed, in a large series of specimens of A. eoncentrica from the Eifel, now before me, 

 some young and old examples appear almost smooth, so fine are the concentric lines and 

 laminae, while in other specimens of the same dimensions these same lines and laminae 

 are strongly marked and developed. 



Professors M'Coy and De Koninck have considered Atrypa decussata and A. indentafa 

 (Sowerby) as synonyms of the species under description ; but, as I have not been able to 

 examine the original examples so named, nor any other specimens of these so termed 

 species, I shall express no positive opinion upon the subject, arid content myself by 

 reproducing the author's original description and figures. 



{Athyris?) Atrypa decussata, Sow. Plate III, fig. 17. (Sowerby, 'Trans. Geol. Soc.,' 



2nd series, vol. v, pi. liv, fig. 5.) 



" Subglobose, slightly compressed; front even, straight ; surface concentrically striated 

 and decussated ; beak of the lower valve very little prominent, with a trifling angle on 

 each side. Loc, Petherwin." 



{Athyris'?) Atrypa indentata, Sow. Plate III, fig. 16. (Sowerby, 'Trans. Geol. Soc.,' 



2nd series, vol. v, pi. liv, fig. C.) 



" Transversely obovate, with an indented front ; the edge of the lower valve elevated, 

 its beak small, prominent. 



" The front of this shell appears as if impressed by the finger, whence its name. The 

 elevation in the margin of the lower valve does not affect the surface of the other. This 

 may serve to distinguish it from A. obovata (' Silur. Syst.,' pi. viii, fig. 9), to which it 

 bears a very close affinity. 



"Loc, Petherwin (with the last, abundant), Barnstaple." 



{Athyris?) Atrypa oblonya, Sow. Plate III, fig. 1. (Sowerby, ' Trans. Geol. Soc./ 



2nd series, vol. v, pi. liii, fig. C.) 



" Oblong-oval, convex, smooth ; front produced, elevated ; the elevation narrow. 

 Loc, Barnstaple." 



c 



