1818.] OF THE UNITED STATES. 439 



by his body the two terminal segments. This adherence 

 was so pertinacious, as to be permanently maintained 

 after submersion in spirits of wine; a circumstance, which 

 combined with the appearance of the living animals, was 

 well calculated to deceive the ordinary observer into a 

 belief of the unity of the two sexes so connected. Thus 

 the thorax of the male appearing to the eye connected 

 to the thorax of the female by a pedicel, would seem, 

 unless minutely examined, to be no other than the abdo- 

 minal portion of the same individual; nor would an ordi- 

 nary magnifier exhibit the truth. 



Section III. LOPHYROPA. Latr. 



Genus CYTHERE. 



Shell bivalve, concealing the head; eyes confluent; 

 antennae two, ciliated; feet eight, 



SPECIES, 



C. bifasciata^. Valves ovate, viewed above and be- 

 neath, lateral view suboval, convex above, somewhat rec- 

 tilinear beneath; a dorsal indentation behind the most 

 elevated part; clothed with minute dense hairs; colour 

 greenish-testaceous, tipped with black, the posterior spot 

 emarginate above when the valves are closed, two black 

 bands, the posterior one a little undulated and connected 

 with the anterior one by a dilated, dorsal line, which 

 terminates a little before the anterior band; antetirKS as 

 long as the valves, cilias obsolete; feet white. 



Length one fortieth of an inch. 



Var. a. Valves dusky green, banded and spotted with 

 darker green, nearly as in the species. 



