334 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Ordek D0C0GL0SSA. 



Suborder ABRANCHIATA. 



Family LEPETIDiE. 



Genus LEPETA Gray. 

 Lepeta Gray, P. Z. S. 1847, p. 168.— Dall, Am. J. Conch, v, 1869, p. 140. 



Subgenus Lepeta DaU ex Gray. 



Lepeta Dall, Mon. Fain. Lepetidae, Am. J. Conch, v, 1869, p. 141. 

 Lepeta caeca. 



Patella cceca O. F. Miiller, Prodr. Zool. Dan. 1766, p. 237 ; lb. Zool. Dan. i, 

 p. 12. 



Lepeta cwca Gray, P. Z. S. 1847, p. 168.— Dall, 1. c. p. 141, pi. 15, f. 4. (Type.) 



Sab. — In Alaska, in 23 fathoms, off the Sea Horse Islands, near 

 Point Barrow, Arctic Ocean north from Bering Strait (Smith! 3 

 specimens). Elsewhere, northern seas of Europe and Eastern North 

 America generally, 10-100 fathoms (Sars)j Massachusetts Bay north- 

 ward, in America. In Europe northward from Danish waters; on the 

 Norwegian coast ; the Hebrides, etc. 



This species has not been found, though reported, erroneously, south 

 from Bering Strait on the Pacific side. Such references refer to L. (C.) 

 concentrica. Jeffreys found it in six hundred and ninety fathoms off 

 Holsteinborg in Greenland, and it ranges from that depth to a few 

 fathoms. That it has a curved, nearly spiral, deciduous nucleus when 

 very young, was announced by me in 18G9, and is confirmed by Dr. Jef- 

 freys in his Report on the Mollusca of the Valorous Expedition. It is 

 the Patella Candida of Couthouy, P. cerea of Moller, and probably the 

 Lepeta Franldini of Gray MSS. 



Subgenus Cryptobranchia Dall ex Midd. 



Cryptobranchia Midd. (pars), Sib. Reise, p. 183, 1851. — Dall, Mon. Lepetidae, 1. c. 1869, 

 p. 143. 



The name Cryptobranchia was previously used by Gray, Fleming, and 

 Deshayes for different groups of mollusks of family or greater value, but 

 has in none of these cases been used or adopted by other naturalists, and 

 hence was not preoccupied for the group of Middendorf. 



Cryptobranchia concentrica. 



Patella ( Cryptobranchia) cceca, var. (3 concentrica, Midd. Sib. Reise, p. 183, pi. 

 xvi, f. 6, 1851. 



Cryptobranchia concentrica Dall,l. c. p. 143, pi. 15, f. 2 a-f. 

 Lepeta ccecoides Cpr. Suppl. Rep. Br. As. 1863, pp. 603, 651. 



Hab. — Xorth Japan, Stimpson! Schrenck!, eastward throughout the 

 Aleutians, along the southern coast of Alaska (Dall!), British Columbia 



