544 nuculipjE. 



Species of Limopsis. 



Belcheri, Adams and Reeve. eancellata, Reeve. 

 borealis, Woodw. multistriata, Forsh 



Fam. NUCULIDjE. 



Lips broad, triangular, large, striated internally, one in 

 each pair of labial palps, long, curled, linear, and fimbriated 

 at its margins, the other short and filiform. Mantle freely 

 open, the edges simple, without siphonal tubes ; gills small, 

 pinnate, united behind. Foot compressed, deeply grooved, 

 forming, when expanded, an ovate disk with serrated edges. 



Shell covered with an epidermis, pearly within. Hinge 

 with two teeth, each numerously and transversely divided ; 

 ligament internal, small, central. Two adductor muscular 

 impressions. 



Genus NUCULA, Lamarck. 



Shell trigonal or obliquely ovate, closed, anterior side 

 the shorter; surface of valves smooth or concentrically 

 grooved, covered with a smooth olive epidermis; nacreous 

 within ; beaks approximated, incurved ; margin of valves 

 smooth or denticulated. Hinge-line angulated, a prominent 

 internal cartilage-pit at the angle; teeth forming a range 

 of comb-like denticles on each side; ligament chiefly in- 

 ternal. Pallial impression simple. 



Syn. Nuculana, Link. Polydonta, Muhlf., not Schum. 



Ex. N. nucleus, Linnmts, pi. 120, fig. 3. Shell, N. 

 nucleus, fig. 3, a, 3, b. 



The species of Nucula are found in all seas, in the 



