PELECYPODA 569 



straight; teeth prominent, 23 on anterior and 18 on posterior side: 

 North Carolina to Labrador in shallow water; common; Pacific coast; 

 Europe. 



Y. sapotilla (Gould). Like the above but much smaller, and with 

 about 16 teeth on each side; 22 mm. long, 11 mm. high and 7 mm. wide: 

 Long Island to Arctic Ocean; often common, in 4 to 120 fathoms. 



Y. thraciaeformis Storer. Shell reniform, rounded and broadest 

 behind, gaping at both ends; 5 cm. long; 4 cm. high, and 27 mm. wide; 

 hinge with about 12 teeth on each side: Long Island to Arctic Ocean; 

 in rather deep water. 



3. Leda Schumacher. Shell elongated, the hinder part being much 

 prolonged; mantle open, with small, united siphons: 80 species, cosmo- 

 politan. 



L. tenuisulcata (Couthouy) (Fig. 894). Shell 25 mm. long, 12 mm. 

 high, and 7.5 mm. wide, light greenish-yellow in color, with 12 anterior 



Fig. 893 Fig. 894 Fig. 895 



Fig. 893 — Yoldia limafula (Verrill). Fig. 894 — <Leda tenuisulcata (Gould). 

 Fig. 895 — Solemya velum (Verrill). 



and 16 posterior teeth: Rhode Island northwards, in shallow water; 

 often common. 



Family 2. SOLEMYIDAE. 



Shell equivalve, elongate, cylindrical, gaping at each end; perios- 

 tracum thick, extending over the edge of the shell; hinge toothless; foot 

 long and slender; oral palps elongate; mantle fused below, leaving an 

 opening for the foot and one hourglass-shaped siphonal opening behind : 

 1 genus. 



Solemya* Lamarck {Solenomya Menke). With characters of the 

 family : several species. 



S. velum Say (Fig, 895). Shell very thin and fragile, j-ellowish- 

 brown in color, with about 15 impressed lines radiating from the umbo 

 to the margin, bluish-white within, 25 mm, long, 12 mm. high, and 8 mm. 

 wide: North Carolina to Nova Scotia; usually buried in the sand; also 

 found swimming backwards and forwards; often common. 



S. borealis Totten. Like the above but much larger and darker; 

 length 5 cm. ; height 22 mm. ; width 14 mm. : Long Island Sound to Nova 

 Scotia; rare. 



* See "Locomotion in Fulononiya," etc., by G. A, Drew, Anat. Anz,, Vol. 17, 1900. 



