92 JOUKISTAL OF THE NEW JERSEY 



external ligament slight, and an internal cartilage in pit between 

 the series of many teeth ; pallia! sinus deep. 



Animal with united, retractile siphons ; foot slightly keeled, 

 deeply grooved, its margins crenated ; mantle margin plain in 

 front and fringed behind. The animal is very active and leaps 

 around in the water in an astonishing way. Deep water, 2-100 

 fathoms. 



1. Yoldia Umatilla, Say. Shell oblong-ovate, the um bones 

 about central and not prominent; posterior dorsal slope straight, 

 making that end quite angular ; anterior and basal margins regu- 

 larly rounded; cartilage pit small; the teeth extend f the 

 length of the shell, 22 on the rounded and 18 on the rostrated 

 end. Epidermis polished, light green ; interior bluish-white, 

 somewhat pearly. L, 47; H. 23; W. 12; U. 4; An. 170°.— 

 Whole coast. 



2. Yoldia sapotilla, Gld. Similar in shape to the preceeding but 

 much smaller ; thin, fragile, translucent ; cartilage pit deep and 

 triangular ; teeth about sixteen on each end. Epidermis highly 

 polished, pale yellowish-green ; pearly-white within. L. 22 ; H. 

 11; W. 7; U. a little in front of centre; An. 160°.— New Eng- 

 land. 



2. Leda, Schum. 



Shell oblong ; rounded in front, pointed behind ; pallial line 

 with small sinus. 



1. Leda pernida, Mul. Shell ovate-lanceolate, front end 

 rounded, hind end much narrowed, rostrated, and slightly turned 

 upward ; dorsal surface with a lanceolate, smooth and shining 

 area behind the umbones; below this, a gonial ridge forms 

 an obtuse fold ; surface with numerous, concentric folds ; car- 

 dinal teeth about 13 in front, and 17 back of the cardinal pit. 

 Epidermis light greenish-yellow ; pearl}^- white within. L. 16 ; 

 H. 7 ; W. 4 ; U. J ; An. 160°.— New England. 



Order TELEODESMACEA. 



Hinge with few transverse or cardinal teeth and usually heavy 

 and strong longitudinal or lateral teeth ; substance of shell 

 always limy or porcellanous, never with pearly layers. 

 Family 8. CARDITID/E. 



Shell thick, solid, roundly ovate, and covered with radiating 



