PELECYPODA 



585 



1. Ltjcina Bruguiere. Hinge teeth consisting of 1 or 2 cardinals 

 and usually 2 laterals in each valve; lunule distinct; foot sometimes 

 twice as long as the animal, and hollow : 100 species. 



L. filosa Stimpson (Fig. 920). Shell thick, regular; hinge margin 

 straight; surface whitish, with prominent lines of growth; 1 cardinal in 

 the left and 2 in the right valve ; no laterals ; length 

 and height 37 mm.; width 15 mm.: Arctic Ocean to 

 Patagonia, in rather deep water. 



2. Cryptodon Turton. Teeth absent ; foot long 

 and very slender: 16 species. 



C. gouldi (Philippi). Shell minute, white, 7.5 



mm. long, 8 mm. high, 2.5 mm. wide: Long Island to ^^ r.o^ r • 



^' *= ' * Fip. 920 — Lacina 



Gulf of St. Lawrence, in 6 to 300 fathoms. )^«osa (Gould). 



Family 8. KELLYELLIDAE. 



Shell minute, thin, equivalve, round or oval; hinge with 1 or 2 car- 

 dinals, a prominent anterior lateral, which is beneath the cardinal, and a 

 posterior lateral, which may be wanting; ligament external; no pallial 

 sinus; mantle open below; anal siphon complete: 1 species on the Atlantic 

 coast. 



TuETONiA Forbes and Hanley. Shell attached by a byssus; shell 

 oval: in northern seas. 



T. minuta (Fabrieius) (Fig. 921). Length 2 mm.; height 1.2 mm.; 

 width 1 mm. ; color yellowish inside and out, blending into purple on the 

 umbo : circumpolar, south to Cape Cod and Alaska ; common under stones 

 at low-water mark and among the roots of seaweed; Europe. 



Family 9. ERYCINIDAE. 



Shell minute, thin, equivalve; hinge with 1 or 2 cardinals of which 

 the anterior one is oblique; laterals not constant; ligament internal; no 

 pallial sinus; mantle united below, with 3 open- 

 ings, a posterior anal opening, a median one for 

 the foot, and an anterior branchial opening; foot 

 long, with byssus; viviparous: marine; 5 genera. 

 Kellia Turton. Shell without pallial sinus 

 and with 1 lateral tooth in each valve: about 35 



Fig. 921 



Fig. 922 



Fig. 921 — Turtonin mi- 

 nuta (Gould). PMg. 922— 

 Kellia planulata (Gould). 



species. 



K. planulata Stimpson (Fig. 922). Shell minute but not very thin, 



oval, white, with a brownish periostracum, 4 mm. long, 3 mm. high, and 



1.5 mm. wide: Arctic Sea to Long Island Sound, under stones and in 



shallow water; not common. 



