MARINE MOLLUSCA OF THE UNITED STATES. 117 



Genus HERMiEA, Loven. 

 Ofvcrs. Kong. Vet. Acad. Ilandl. 1844. 



1. H. cruciata, Ale^;. Agassiz. Fig. 242. 



Could, Invert. Mass., edit. ii. 258, t. 17, f. 256. 1870. 



Booty very slender, the tail much attenuated; foot narrower 

 than the body, obtusely dilated at the anterior angles ; head small, 

 semicircular; mouth inferior; tentacles dilated and obtusely 

 pointed, the superior face longer than the inferior ; branchiae di- 

 lated, shaped much like trefoil or the ace of clubs, the biliary 

 organs within having a rude cruciate form ; there are seven prin- 

 cipal ones on each side, and eight or ten intermediate much 



Massachusetts. 



smaller ones 



Genus ALDERIA, Allraan. 

 Thompson, Rep. Faun. Ireland. 1844. 



1. A. Harvardiensis, Agassiz. Fig. 243. 



Gould, Invert. Mass., edit. ii. 254, t. 10, f. 220-228. 1870. 

 Animal broad lanceolate, ochreous-brown ; foot yellow ; lateral 

 prolongations of head tentacular; branchiae short, curved, en- 

 larging towards the tips, in about six clusters, of two each, on 

 either side, of which the lower one is much smaller. 



Length 12, breadth 4 mill. 



Massachusetts; Grand Ma nan. 



Genus CL(ELIA, Loven. 

 . Embletonia, Alder and Hancock, Ann. Mag., viii. 294. 1851. 



1. C. fuscata, Gould. Fig. 244. 



{Embletonia.) Invert. Mass., edit. ii. 251, t. 16, f. 229-232. 1870. 

 Animal subcylindrical, narrowing backwards; tail short, pointed, 

 drab-colored; head larger than bocty, broad angles rounded, 

 slightl}- emarginate ; tentacles short; branchiae club-shaped, ar- 

 ranged in Qve or six tufts on each side of the posterior portion 

 of the body ; angles of foot not dilated. 



Length 4, breadth .66 mill. 



Massachusetts. 



2. C. remigata, Gould. Fig. 245. 



{Embletonia.) Invert. Mass., edit. ii. 252, t. 10, f. 214-217. 1870. 

 Animal long, slender, uniform pale-3'ellow ; head large, emargi- 

 nate, angles dilated into triangular lobes with blunt points ; ten- 



