212 LUCINID^. 



kind of a roundish or spoon-shaped process below the beaks ; 

 muscular impressions rounded. 



Subfamily COBBING. 



Shell generally elongately ovate, or ovately rounded, solid, 

 with muscular impressions subequal, broadly ovate, the ligament 

 alwaj^s external. 



CoRBis, Cuvier, 1811. 



Etym. — Gorhis^ a basket. 



Syn. — Fimbria, Miihl., 1811, not Bohadsch. Idotsea, Solium., 

 18n. Gafrarium, Bolten, 1798. 



Dist?-. — 5 sp. India, China, North Australia, Pacific. Fossil, 

 80 sp. (including subgenera^). Lias — ; United States, Europe. 

 C. Jimbriata, Linn, (cxix, 51). 



Shell oval,ventricose,subequilateral, concentrically sculptured ; 

 margins denticulated within ; hinge-teeth two, laterals two, in 

 each valve ; pallial line simple ; umbonal area with an oblique 

 furrow, muscular impressions round and polished ; pedal scars 

 close to adductors. 



Animal with the mantle open below, doubly fringed ; foot lon,g, 

 pointed ; siphonal opening single, with a long retractile tubular 

 valve ; lips narrow ; palpi rudimentary ; gills single on eaieh 

 side, thick, quadrangular, plaited, united behind. 



In G. dubia (Semicorbis), Desh., from the Eocene, Paris, the 

 lateral teeth are obsolete. 



SPH^RA, Sow., 1822. (Palseocorbis, Conrad, 1869.) Shell 

 ovate, inflated, solid, subeqnilateral ; hinge of left valve with two 

 blunt cardinal teeth, the posterior much smaller and separated 

 from the larger anterior by a pit ; lunnlar edge somewhat extended 

 with a deep pit and a swollen tooth-like margin above and below 

 it ; posteriorly with a furrow near the fulcral margin and several 

 cross-teeth at the posterior end ; ligament in a long excavated 

 furrow. Type, G. corrugata^ Sowb. (cxix, 52 . Neocomian. 



MUTiELLA, Stolicz., 1870. Shell oblong, subequilateral, tumid, 

 with obtuse incurved beaks ; hinge in the left valve with two 

 cardinal teeth, the anterior one being sometimes bifid, in the 

 right valve there is a single large bifid cardinal tooth ; lunular 

 edge expanded, with several teeth, or with more or less distinct 

 corrugations, representing anterior lateral tooth ; posterior hinge 

 side straight with a furrow near the margin for the ligament, and 

 an indistinct terminal posterior lateral tooth. G. coar.ctata^ 

 Zitt. (cxix, 56, 57). This group differs essentially by the char- 

 actei's of the hinge from the previous; there are several middle 

 and upper cretaceous species which belong to it, but none are 

 known from more recent deposits. 



SPH^RiOLA, Stoliczka, 1870. Shell rounded, globose, nearljr 

 equilateral, with concentric striae or sulci on the surface ; hinge 



