504 CYMBULIIDJE. 



Diacria trispinosa. 



Shell long, straight, anteriorly dilated, compressed on both sides, terminating 

 posteriorly in a very long spine, and armed with a short spine on each side. 



Hyalea trispinosa, Lesueur, in Blainville, Diet. xxii. 82. — Forbes and Hanley, 

 Brit. Moll. 11. 380, pi. 5, tig. 3. — Stimfson, Shells of New England, 27, no dcscr. 

 (18.51) ; Check Lists, 4 (1860). 



Diacria trispinosa, Gray, Brit. Mus. Pteropods. 



This species is admitted on the authority of Dr. Stimpson, who 

 says specimens are occasionally cast ashore at Nantucket. 



Family CYMBULIIDyE. 



Animal globular or ovate. Fins two, horizontal, opposite on each 

 side of the mouth, with a small intermediate lobe. 



Shell cartilaginous, slij)pcr-shaped, rarely wanting. 



This family comprises four singular pelagic genera with mem- 

 branous or cartilaginous shells, excepting Tiedemannia, which does 

 not appear to possess any mcmln'anous envelope. 



Cicnus PSYCHE, Rang. 182G. 



Body free, membranous, without any distinct head ; tentacles 

 none ; wings two, lateral, elongate, without any intermediate lobe. 

 Shell very thin and membranaceous. 



Psyche globiilosa. 



Psyche c/iobulosa, Rang, Ann. Sc. Nat. 1st ser. v. 283 (1825). — Rang and Souleyet, 



Hist. Nat. des Pterop. 72, pi. 7, fig. .5 (1852). — Gray, Br. Mns. Pter. 28 (1850). 

 Euribia globulosa, Gray, Brit. Mus. Moll. coll. Eydoux and Souleyet, 11 (1855). 



Body round, diaphanous, mouth slightly arched, fins long, rounded 

 at their extremity, narrowed at their base, with a light shell-case 

 above. Viscera of a handsome purple, forming an ovoid mass, 

 suspended in the middle of the body. {Rang-.^ St. Pierre and 

 Miquclon. 



Family LIMACINIDyE. 



Animal elongate, spiral ; the head indistinct ; mouth at the union 

 of the two fins and intermediate lobe, with two small labial swell- 



