MARINE MOLLUSKS — MACGINITIE 73 



Class Gastropoda 



Subclass Streptoneura 



Order Aspidobranchia 



Suborder DocoGLOSSA 



Family Lepetidae 



G^nus Lepeta Gray, 1847 

 Lepeta caeca (Miiller, 1776) 



Plate 4, figures 1, 1a 



Patella caeca Miiller, 1776, p. 237. 



Lepeta caeca Jeffreys, 1865b, p. 252, pi. 5, fig. 6.— G. Sars, 1878, p. 123, pi. 20, 



figs. 17a, b.— Morris, 1947, p. 73, pi. 25, fig. 2; 1951, p. 106, pi. 25, fig. 2. 

 Lepeta alba Dall, 1870a, p. 145, pi. 15, figs. 3a-d. 

 ILepeta alba instabilis Dall, 1870a, p. 145, pi. 15, fig. 6. 

 Lepeta coeca Odhner, 1912, pp. 12, 32, pi. 2, figs. 2-17. 



Thirty-four specimens, eight of which were dead shells, were dredged 

 from depths ranging between 125 and 477 feet, the majority coming 

 from 217 feet (10 living specimens) and deeper. The shells range in 

 length from 5.5 to 11.0 mm. The measurements of several shells 

 are as follows: 10.3 long by 7.8 wide by 4.8 mm. high; 10.1 by 7.8 by 

 4.5 mm.; 10.0 by 7.6 by 4.8 mm.; 9.1 by 7.1 by 4.1 mm.; and 8.8 

 by 6.6 by 3.8 mm. 



Other material examined: Seventy specimens from Norway, 

 Greenland, Labrador, Newfoundland, Green Bank in the Bay of 

 Fundy, Frenchman's Bay, Maine, near Cape Gaspe, and the east 

 end of Cabourg Island in Baffin Bay. About 25 specimens (all dead 

 shells) from localities ranging from the Sea Horse Islands, Alaska, 

 to Captain's Harbor in the Aleutians (lat. 55° N.). 



Discussion: These specimens correspond with those collected at 

 Point Barrow. Three specimens from western Norway are a trifle 

 flatter and in one the apex is somewhat nearer the center than usual, 

 but these variations are within normal limits. 



There has been a great deal of confusion regarding the northern 

 species of Lepeta. In L. caeca the posterior slope is nearly always 

 markedly convex, and the anterior slope is straight (pi. 4, fig. 1a) and 

 never slightly concave as in L. concentrica and L. caecoides. The 

 radiating lines of striae in L. caeca are granular, the granulation 

 varying in coarseness. L. caeca is relatively higher than L. concentrica 

 and L. caecoides. For example, a specimen of L. caecoides measuring 

 10.4 mm. long by 8.0 wide is 3.3 mm. high, and a specimen of L. caeca 



