464 MANTJAL OF THE MOLLUSCA. 



Synonym, Arctica, Scliuin. 



Shell oval, large and strong, witli usually an oblique line or 

 angle on the posterior side of each valve ; epidermis thick and 

 dark ; ligament prominent , umbones oblique ; no lunule ; 

 cardinal teeth 2.2, laterals — 1, 1 — 0; muscular impressions 

 oval, polished ; pallial sinus obsolete. 



Animal with the mantle ojDen in front and below, margins 

 plain; siphonal orifices close together, fringed, slightly pro- 

 jecting ; outer gills semilunar, inner truncated in front. 



The principal hinge-tooth in the right valve of Cyprina 

 represents the second and third in Venus and Cytherea ; the 

 second tooth of the left valve is consequently obsolete. 



Distribution, C. Islandica ranges from Greenland and the 

 United States to the Icy Sea, Norway, and England ; in 5 — 80 

 fathoms water. It occurs fossil in Sicily and Piedmont, but not 

 alive in the Mediterranean. 



i^ossfZ, 90 species. (D'Orbigny.) Muschelkalk — . Europe. 



ClECE, Schumacher. 



Etymology, in Greek mythology a celebrated enchantress. 



Example, 0. corrugata, PI. XX., Fig. 2. 



Synonym, Paphia (undulata), Lamarck.* 



Shell sub-orbicular, compressed, thick, often sculptured with 

 diverging strise; umbones flat; lunule distinct; ligament 

 nearly concealed ; margins smooth ; hinge-teeth 3:3 ; laterals 

 obscure ; pallial line entire. 



Animal (of C. minima) with the mantle open, margins denti- 

 culate, siphonal orifices close together, scarcely projecting, 

 fringed ; foot large, heeled ; palpi long and narrow, Ranges 

 from 8 — 50 fathoms. (Forbes.) 



Distribution, 40 species. Australia, India, Red Sea, Canaries, 

 Britain. 



AsTAETE, Sowerby, 1816. 



Synonym, Crassina, Lamarck. Tridonta, Schum. Goodallia, 

 Turton. 



Example, A. sulcata, PI. XX., Fig. 1. A. borealis, Fig. 258. 

 [Astarte, the Syrian Yenus.) 



Shell sub -orbicular, compressed, thick, smooth or concent 



* This name was employed by Bolten, in 1798, for sp. of Veneridce, and by Lamarck, 

 in 1801, for Venus divaricata, Chemn. (= Circe divaricata and Crassatella contraria), 

 and Mesodesma glabratum. In 1808, Fabricius adopted the name for a group of butter- 

 flies, in wliicb sense it is now widely employed, having been abandoned by Lamarck in 

 tiis later works, and by a)l succeeding malacologists. 



