ERVILIA. 345 



the shell, it becomes convex or even subarcuated. The pos- 

 terior side is about half as long again as the anterior. The 

 beaks are very acute, moderately prominent, not leaning to either 

 side, and preceded and succeeded by a small depression, but no 

 distinct lunule nor escutcheon. 



The hinge consists in the right valve of a very strong highly- 

 projecting primary tooth situated just in front of the apex, which 

 is subtriangular in shape, and directed forward, in front of which 

 the hinge margin, which is very thick and strong, is somewhat 

 excavated ; behind it, and exactly beneath the apex, is the large 

 triangular cartilage cavity, the front edge of which is perpendi- 

 cular, and the hinder very oblique ; there is also a fine linear ex- 

 cavation running along the posterior hinge margin. In the other 

 valve, the margin on either side of the beaks is elevated so as to 

 simulate two laminar diverging teeth, the broadly-triangular 

 interstice being divided into a narrow and trigonal hollow for the 

 reception of the opposite tooth, and a broader cartilage plate 

 which projects in front beyond the basal line and whose anterior 

 edge is elevated so as to resemble a linear tooth. The cartilage 

 is inserted between a cut in the apices. The ordinary length is 

 about three-eighths of an inch, and the breadth about one-fifth, 



A West Indian shell, introduced hy Montagu as taJcen near 

 Dunbar by Mr. Laskey. It is not unimportant to remark, as 

 accounting in some measure for the very considerable mi/inber of 

 exotic shells introduced from the neighbourhood of Dunbar by 

 Mr. Laskey, that several vessels from foreign 23orts had, just before 

 that gentlematis investigation, visited his subsequent dredging- 

 ground, and their ballast was in all probability the fertile source of 

 most of his additions to British Conchology, as it has in like 

 manner added not a few spurioxis species to the Flora of the neigh- 

 bouring district. 



* An ErviJia jxllucida has been added to this genus by Professor Macgillivray, 

 which we vainly hoped to have examined before the publication of this sheet, as 

 that gentleman had promised to forward us any of his species we might desire to 

 investigate. Judging only from the description, we feel little doubt that it is 

 merely the fry of a described species, and certainly not the Tellina pdlucida of 

 Brown, to which it was referred in the Molluscous Animals of Aberdeenshire, &c. 

 (p. 341, copied in the British Marine Conchology, p. 245,) which is a full 

 quarter of an inch in length, and smooth in surface, &c. ; while this is described 

 as being but three-fourths of a line only, and concentrically sulcated. We owe to 

 the kindness of Sir Walter Trevelyan (who found it at Seaton, in Durham,) an 



VOL. I. y Y 



