LEPTON. 201 



hairs, which are so delicate as to be almost invisible, is 

 not less worthy of admiration than its larger and more 

 showy congener. 



B. Shell concentrically grooved, or marked with fine longitu- 

 dinal lines. 



3. L. sulca'tulum *, Jeffreys. 



L. sulcatuhim, Jeffr. in Ann. Nat, Hist. 3rd ser. Jan. 1859, p. 34, pi. 2. 

 i.2a-g. 



Body of a light yellowish-brown colour. 



Shell nearly circular, the contour being interrupted only 

 by the prominence of the beaks, somewhat compressed, thin, 

 semitransparent and glossy: sculpture, broad, numerous and 

 regular concentric ribs, which are equally strong and distinct 

 throughout the surface, and still more numerous and fine lon- 

 gitudinal lines, which are not perceptible by the naked eye : 

 colour clear white : epidermis filmy : margins rounded at the 

 sides and in front, with a gentle fall from the beak to each 

 end : beaks projecting a little beyond the dorsal margin, slightly 

 inclined towards the narrower and shorter side : lunge-line 

 obtusely triangular, occupying scarcely one-fourth of the cir- 

 cumference : cartilage small, placed close to the beak on the 

 shorter side : hinge-plate broad and thick, not much excavated 

 for the reception of the cartilage : teeth, one strong and erect 

 cardinal in the left valve, and a much smaller one in the right 

 valve, besides a remarkably strong and triangular lateral on 

 each side of the beak in both valves ; that on the broader side 

 is longer than the other ; the grooves into which these lateral 

 teeth lock are correspondingly deep : inside nacreous and 

 glossy, with a plain margin : scars rather distinct. L. 0*055. 

 B. 0-06. 



Habitat : Rather plentiful among corallines in the 

 laminarian zone at Guernsey. I also found it at 

 Etretat on the coast of Normandy, as well as among 

 some small shells from Sardinia which I received from 

 M. Hupe for examination ; and I noticed specimens in 



* Slightly furrowed. 



K 5 



