CONCHIF ERA. 47% 
Shell orbicular, compressed, concentrically striated, pale 
ligament sunk; lunule deep; hinge lke Cytherea; margins 
even; pallial sinus deep, angular, ascending. 
Animal with a large hatchet-shaped foot, projecting from the 
ventral margin of the shell; mantle-margins slightly plaited ; 
siphons united to their ends; orifices simple; palpi narrow. 
Distribution, 100 species. Boreal—Tropical seas; low water 
80 fathoms. 
Fossil, 13 species. Carb—. United States, Europe, South 
India. 
Sub-genera. Cyclina, Desh. Y. Sinensis, Chemn. Orbicular, 
ventricose, margins crenulated, no lunule, sinus deep and 
angular. Distribution, 10 species, Senegal, India, China, 
Japan, West America. Jossi/, 1 species. Miocene, Bordeaux. 
Clementia (papyracea) Gray. Thin, oval, white; lgament 
semi-internal; posterior teeth bifid, sinus deep and angular. 
Animal with long, united siphons, and a large crescentic foot, 
sunilar to Artemis. Distribution, 6 species. Australia, Philip- 
pines. 
Lucinopsis, Forbes. 
Synonyms, Dosinia, Gray, 1847 (not Scop.). Mysia, Gray, 
1851 (not Leach). Cyclina, Gray, 1853 (not Desh.). 
Type, Venus undata, Pennant, Pl. XX., Fig. 13. (Lucina 
and opsis lke.) 
Shell lenticular, rather thin; right valve with 2 laminar, | 
diverging teeth, left with 3 teeth, the central bifid; muscular 
impressions oyal, polished; pallial sinus very deep, ascending. 
Animal with mantle-margins plain; pedal opening con- 
tracted ; foot pointed, basal; siphons longer than the shell, 
separate, divergent, with fringed orifices. (Clark.) 
The type of this genus haying been erroneously placed in 
Cyclina by M. Deshayes, he has proposed a new genus (Lajon- 
kairia) for L. decussata, Philippines, a fossil of the English 
Pliocene, but still hying in the Mediterranean. 
Distribution, 10 species. North America, Norway, Britain. 
Fossil, 3 species. Pliocene. Britain, Belgium. 
TapEs, Miihlfeldt. 
Synonyms, Paphia, Bolten, 1798. Pullastra,G.Sby. Omalia, 
Ryck, 1856. 
Ezample, T. pullastra, Pl. XX., Fig. 14. (Tapes, tapestry.) 
Shell oblong, umbones anterior, margins smooth; teeth 3 in 
cach yalye, more or less bifid; pallial sinus deep, rounded. 
