550 RADULID.E. 



Genus HEMIPECTEN, Adams and Reeve. 



Shell inequivalve, irregular, hyaline, the superior valve 

 slightly anriculated, the inferior valve posteriorly con- 

 spicuously auriculate, deeply sinuated and denticulate 

 beneath the auricle. Hinge edentulous ; ligament mar- 

 ginal; cartilage small, in a central cavity. 



Ex. H. Forbesianus, Adams and Reeve, pi. 127, fig. 5, 

 5, a. 



In this genus the margin of the sinus, as in many 

 species of Pecten, is furnished with a row of sharp erect 

 denticles. From the Anomia-like appearance of the shell, 

 it probably lives attached to foreign bodies. The single 

 species known is from the Sooloo Archipelago. 



Fam. RADULID^E. 



Body produced, in part linguiform. Mouth surrounded 

 by tentacular filaments. Mantle without any ocelli on the 

 edge, the margin fringed with tentacular filaments; anal 

 tube cylindric, visible externally. Foot compressed, not 

 byssiferous. 



Shell gaping at the sides, usually white. Hinge eden- 

 tulous. 



Genus RADULA, Klein. 



Shell more or less obliquely oblong, equivalve, closed in 

 front, more or less gaping at the sides ; surface of valves 

 usually grooved in a radiating manner, the ribs scaly ; 



