CONCHIFEEA. 



249 



a thick mantle, and small opening for 

 the foot ; mouth having two large tri- 

 angular tentacles, and there are two 

 long, nearly equal gills. — 1 species. 



G. siliqua is found in the North- 

 ern Seas, on sands, and is the only 

 species. 



Tellinomya. Hall — Shell equivalve, inequilateral, 

 beneath somewhat compressed, but lengthened near the 

 bosses, the outline curved or angular; the shell is thin, 

 furnished with thick lamellaa ; the hinge without visible 

 teeth, or even a furrow : two muscular impressions near 

 the hinge ; the hinder extremity often gaping ; the pallial 

 impression not known. — Fossil. 



Arcinella. Philippi. — Shell equivalve, inequilateral, 

 transversely oval; the bosses small, a little protruding; 

 hinge without teeth; the upper edge of the right valve 

 extends very far into the shell, and has a broad triangular 

 notch under the boss (for an inner ligament?), behind 

 which are two radiating ledges extending from the bosses; 

 the left valve has its hinge edge on the projecting edge of 

 the right ; the ligament, muscular, and pallial impressions 

 unknown. — Fossil. 



Family 6. — SOLENACEA. 



The animals of this family live buried in sand; the 

 siphons are in some genera joined together, in others 

 separated ; the foot is thick, cylindrical, club-shaped, or 

 compressed; the gills are lengthened, and floating with 

 the point free in the breathing tube. The shell is regular, 



