NYMPHACEA. MOLLUSCA. LUCINA. 69 



semi-oval before the beaks ; the posterior slope sudden and nearly 

 straight, forming a blunted angle by its junction with the base ; 

 marginal fold well marked ; surface regularly and delicately mark- 

 ed by sharp lines of growth ; color white, or slightly tinged with 

 rose-color, and iridescent ; ligament short and prominent ; cardi- 

 nal teeth two in each valve, the posterior one of the left valve 

 rudimentary, the principal one in each valve grooved ; lateral 

 tooth on the longer side distinct ; that on the shorter side, just 

 behind the ligament, scarcely perceptible ; sinus of the palleal 

 impression nearly reaching the anterior palleal impression. Length 

 ? inch, height ^ inch, breadth T 5 T inch. 



Found abundantly cast upon all our sandy beaches, and prob- 

 ably lives not far from low-water mark. 



It is a very pretty little species, its beauties becoming developed by 

 examination. There are two other species closely allied to it ; the T. 

 polita, which is a somewhat larger and stronger shell, its posterior 

 angle more prolonged and sharper, and its surface smooth, glossy, 

 porcelain-white ; also T. iris, of about the same size, solidity, and 

 color, but its surface is marked by oblique grooved lines which at 

 once distinguish it. This is not found on our shores, nor am I cer- 

 tain that T. polita has been. It is not likely to be confounded with 

 any other shell. 



GENUS LUCINA, BRUG. 



Shell rounded, beaks small ; two diverging cardinal teeth, one 

 of which is bifid, and usually two lateral teeth, one of them near the 

 cardinal teeth, in each valve ; there is sometimes a posterior angle, 

 but never a fold, as in Tellina ; palleal impression without a 

 sinus. 



LucfNA RA'DULA. 



Shell orbicular, compressed ; surface with numerous concentric, 

 laminated strict ; lunule depressed, lanceolate ; lateral teeth wanting. 



State Coll., No. 213. Soc. Cab., No. 2330. 



Tellina radula, MONTAGU ; Test. Brit., 68, pi. 2, f. 2. PENNANT ; Brit. ZooL, iv. 

 181. RACKETT ; Lin. Trans., viii. 54. WOOD ; Gen. Conch., 183, pi. 42, 

 4,5. TURTON; Brit. Biv ,116. Conch. Diet., 175. CHEMN. ; Conch., vii. 1C, 



