480 CRYPTOPLACINiE. 



everywhere covering the back and containing fascicles of 

 bristles. A single species only is known, from the shores 

 of Kamtschatka. 



Sub-fam. CRYPTOPLACIN^. 



Mantle with a double series of pores beset with horny 

 bristles, or a single series of pores furnished with tufts of 

 calcareous spines. 



In this sub-family the general similarity of the animals 

 to the annulose tribes is even more striking than in the 

 last division, on account of the tufts of spicula surround- 

 ing the pores along the sides of the mantle. Tliere are 

 four genera, not very numerous in species, and all remark- 

 able for the large portion of the valves covered by the 

 mantle. 



Genus AMICULA, Gray. 



Mantle covered with scattered fascicles of hairs, and 

 having two series of setigerous pores ; gills posterior. 



Shell with the valves externally scarcely conspicuous, 

 the exposed parts small, sub-cordate, as broad as long. 



Ex. A. vestita, Sowerhy, pi. 55, fig. 2. 



In this genus the shell is concealed under the mantle, 

 except in the median dorsal line, where the valves are free 

 from the mantle and conspicuous externally ; the plates 

 of insertion are similar to those of Cryptoconchus. There 

 are four species described, all from northern shores. 



