NUCULA. 149 



3. N. ni'tida*, G. B. Sowerby. 



X. nitida, Sow. Conch. 111. (Nucula) p. 5, f. 20 ; F. & H. ii. p. 218, pi. xlvii. 

 f. 9. 



Body similar to that of N. nucleus ; but the gills are light 

 brown, smoother outside, and more strongly striated on the 

 inner surface : foot of a paler colour, and its disk less deeply 

 serrated at the margin. 



Shell acutely triangular, convex towards the beaks, but 

 compressed in front, moderately solid, remarkably glossy : 

 sculpture nearly the same as in jV. nucleus ; but the longi- 

 tudinal striae are slighter, and the transverse striae are stronger, 

 especially at the sides, giving the surface a partly cancellated 

 or notched appearance at the points of intersection ; the lunule 

 is only marked by the lines of growth, and the dorsal area is 

 smooth: colour milk-white under the epidermis, which is 

 yellowish-brown, highly polished and lustrous, without any 

 trace of the microscopical lines or wrinkles observable in 

 the foregoing species; the latter is sometimes beautifully 

 tinted with yellow or purplish -brown longitudinal streaks, 

 which are arranged in irregular bundles, and resemble the 

 rays of the setting sun : margins truncate on the anterior 

 side, forming an obtuse angle where it joins the ventral range, 

 rounded in front, and slightly produced or wedge-shaped at 

 the posterior side : beaks prominent, apparently overhang- 

 ing the anterior margin owing to its truncature, and re- 

 curved : lunule as in the last species, but deeper immediately 

 below the beaks, and not so much raised, separated from the 

 rest of the shell by a blunt ridge in each valve : ligament very 

 slight: cartilage pear-shaped; cavity larger and projecting 

 more than in the last species : hinge-line slightly curved : 

 hinge-plate rather narrow : teeth long, sharp, and recurved, 

 about twelve on the anterior, and twenty on the posterior 

 side : inside highly nacreous and iridescent, conspicuously 

 striated lengthwise, strongly notched on the ventral and 

 anterior margins, but the crenulations do not extend to the 

 posterior angle : muscular scars oval, not very distinct. L. 0*4o. 

 B. 0-45. 



Habitat : With the last, but neither so generally dif- 

 fused nor so plentiful. I have taken it at low spring-tides, 



* Shining. 



