Mr. R. Etheridge, Jun., on Gasteropoda. 289 



In some places, probably where the superficial calcareous 

 layer is thin, the pearly iridescence beneath it is observable. 

 The oblique flexuous costas are about nineteen in number on 

 the penultimate, and a trifle more numerous upon the last 

 whorl. 



Yoldia Vancouver ensis. 



Shell almost equilateral, transversely elongate-oval, acumi- 

 nated posteriorly, slightly gaping at both ends, clothed with a 

 greenish olivaceous epidermis, which is darker towards the 

 ventral margin and varied at intervals with dark zones. 

 Surface not very glossy, marked with concentric lines of 

 grovvthand close microscopic striation and granulation. An- 

 terior side a trifle the longer, regularly rounded at the margin, 

 posterior more acute. Hinder dorsal slope nearly rectilinear, 

 scarcely arcuate. Area distinct. Length 12 millims., width 

 224, diam. 6. 



This species is narrower posteriorly than Y. arctica, Gray, 

 which it somewhat resembles, less glossy, and is very minutely 

 granular upon the surface, this sculpturing being only discern- 

 ible under a powerful lens. 



XXXV. — Notes on the Gasteropoda contained in the Gilbertson 

 Collection, British Museum, and figured in Phillips's 

 1 Geology of Yorkshire.'' By R. Etheridge, Jun., 

 F.R.Ph.S.Ed. 



[Continued from vol. v. p. 485.] 



The Species figured on Plate XIV. 



Patella scutiformts, Phillips (p. 223, t. 14. fig. 1). 



The figure is drawn from a somewhat crumpled and frag- 

 mentary specimen, which bears a considerable resemblance to 

 the subject of the next figure, P. sinuosa. From this imper- 

 fection the species will not be easy of recognition in collec- 

 tions, as it is impossible to say what the exact outline was, 

 whether the margin was entire or sinuous. It certainly ap- 

 pears to be rounder than P. sinuosa, more depressed and to have 

 a smaller apex ; it is, however, a question, I think, whether 

 these forms can be retained as more than varieties of one 

 another. Professor M'Coy appears to consider P. scutiformts 

 a good species, from its depressed form and marginal apex. I 

 would, however, observe that in the absence of the broken end 



