BY E. M. JOHNSTON, F.L.S. 



105 



(lxxiv.) Family Coebulidjb. 

 Shell small, inequivalve, thick, gaping in front; hinge con- 

 sisting of a single recurved tooth in one valve, received 

 into a fosset or notch in the other. 



Genus Cokbttla. (572-573.) 

 Shell thick, inequivalve, gibbose, closed, produced posteriorly ; 

 right valve with a prominent tooth in front of the 

 cartilage pit ; left valve smaller, with a projecting 

 cartilage process ; pallial sinus slight ; pedal scars 

 distinct from the adductor impressions. Dist. — 

 United States, Norway, Britain, Mediterranean. 



Genus Ne.<eea. (574.) 

 Shell globular, attenuated, and gaping behind ; right valve a 

 little the smallest ; umbones strengthened internally 

 by a rib on the posterior side ; cartilage process 

 spatulate in each valve (furnished with a movable 

 ossicle — Deshayes), with an obsolete tooth in front, 

 and a posterior lateral tooth ; pallial sinus very shallow. 

 Dist. — Norway, Britain, Mediterranean, Canaries, 

 Madeira, China, Moluccas, New Guinea, Chili ; from 

 12-200 fathoms. 



(Ixxv.) Family Anatinid^:. 

 Shell often inequivalve, thin, interior nacreous ; surface 

 granular ; ligament external, thin ; cartilage internal, 

 placed in corresponding pits and usually furnished 

 with a free ossicle ; muscular impressions faint, the 

 anterior elongated ; pallial line usually sinuated. 



Genus Anatina. (575-578.) 



Shell oblong, ventricose, sub-equivalve, thin and translucent, 

 posterior side attenuated and gaping ; umbones 

 fissured, directed backwards, supported internally by 

 an oblique plate ; hinge with a spoon-shaped cartilage 

 process in each valve, furnished in front with a 

 transverse ossicle ; pallial sinus wide and shallow. 

 Dist. — India, Philippines, New Zealand, Japan, United 

 States. 



Genus Mtodoea. (579-583.) 



knell trigonal, rounded in front, attenuated and truncated behind ; 

 right valve convex, left flat ; interior pearly ; cartilage 

 narrow, triangular, between two tooth-like ridges in 

 the left valve, with a free sickle-shaped ossicle ; pallial 

 line sinuated ; structure like Anatina ; outer cells 

 large, rather prismatic. Dist. — New Zealand, New 

 South Wales, Philippines. 



