476 K. J. Jhi.sk — Mollusca of Cope Satteras. 



rounded ends and with the opposite margins nearly parallel. Beaks 

 very small, incurved, situated near the anterior third ; the dorsal 

 margin in front of the beaks, straight, and behind them slightly ob- 

 lique. Surface somewhat lustrous, roughened by the irregular lines 

 of growtli and cut by nuniei-ous, fine, wavy, diagonal lines, the first 

 one commencing just behind the beaks, and extending to the anterior 

 ventral margin ; near the posterior end of the shell, over the portion 

 radiating from the beaks to the posterior ventral margin, they 

 abruptly turn down in the opposite direction. In a specimen about an 

 inch long there are about thirty-six of these lines. Extending fiom 

 the beaks obliquely backward across the shell there are two very 

 faint, slightly raised, narrow, divergent rays. The hinge in the right 

 valve consists of two unequal, prominent, divergent teeth. The first 

 one, directly under the beak, is a three-sided, pointed tooth, project- 

 ing inward and upward like a hook ; immediately back of this is a 

 very narrow, gradually widening, sharp-edged, very oblique ridge, 

 which forms the second tooth. Back of these, curving strongly 

 inward and upward, is a short, high, angulated, tooth-like process, to 

 the very concave exterior surface of which the ligament is attached. 

 In the left valve, immediately under the beak, attached to the end of 

 the ligamental process, there is a prominent, very thin, leaf-like tooth, 

 curving strongly upward and backward. 



In voung specimens the lines of growth and the oblique markings 

 show very distinctly on the interior, but in more mature examples 

 these are concealed by a layer of smooth, very lustrous, pure white en- 

 amel. Pallial line distinct, with a broad, deep, very conspicuous sinus. 



Color, opaque bluish white, under a thin, closely adherent, lustrous, 

 light yellow epidermis. 



Length of the largest perfect specimen, 30'"™ ; height, 13""" ; thick- 

 ness, about 4'""\ 



Several valves of young specimens were found in 15 to 17 fathoms. 

 At station 2273 a fragment occurred showing the shell to be large and 

 very thick when full grown. 



Tellina lintea Conrad. 



Joum. Acad. Nat. Sci. Philadelphia, vol. vii, [). 25!», pi. 20, tig. ;{, 18;'.7. 

 Common in 10 to 26 fathoms. 



Semele lata c. b. Adams. 



One valve (No. 40,600) agreeing ])erfectly with specimens labelled 

 as this species in the Peabody Museum of Yale College, was found at 

 station 2290, in 10 fathoms. 



