PECTINIDA. ; 291 
very characteristic, and so is also the small marginal cartilage- 
pit. 
Hinnites, Defrance, 1821. 
Distr.—4 sp. Europe, California, etc. Fossil; Triassic—. 4H. 
sinuosus, Lam. (cxxxili, 22, 23). 
Shell oval, irregular, inequivalve, subequilateral, close, 
adhering by the right valve; eared irregularly ; hinge without 
teeth ; ligament thick, in a deep, narrow pit. 
Differs from Pecten in its irregular growth, and in being 
adherent. 
AVIcULOPECTEN, M’Coy, 1852. 
Syn.—? Aphania, de Koninck. 
Distr.—Fossil. Devonian—Carb.; Spitzbergen—Australia, 
N. America. A. granosus, Sowb. (cxxxii, 5). 
Shell inequivalve, suborbicular, eared; hinge-areas flat, with 
several long, narrow cartilage-furrows, slightly oblique on each 
side of the umbones; right valve with a deep and narrow byssal 
sinus beneath the anterior ear; adductor impression large, 
simple, subcentral; pedal scar small and deep, beneath the 
umbo. 
Aviculopecten does not possess the prismatic structure of the 
Aviculidz, but the peculiar corrugated tubular structure of the 
Pectinide (Meek’. It bears the same relations to existing Pec- 
tens as Pterinea does to existing Aviculas. 
PTERINOPECTEN, Hall, 1883. Hinge-line long; wings not well- 
defined, being simple expansions or extensions of the upper 
lateral margins to the hinge-line. 5sp. Hamilton and Chemung 
Groups; New York. A. undosus, Hall. 
EUcHONDRIA, Meek, 1874. Uncharacterized. Type, Aviculo- 
pecten neglectus, M. and W. (exxxii, 7, 8). Carboniferous; Ills. 
LYRIOPECTEN, Hall, 1883. Differs from Aviculopecten in the 
short hinge-line and very small anterior wing; surface usually 
ornamented with strong rays. 5 sp. Chemung and Hamilton 
Groups; New York. A. magnificus, Hall. 
PERNOPECTEN, Winchell, 1865. 
Etym.—Perna and Pecten, from a combination of some of the 
characters of the two genera. Syn.—Entolium, Meek, 1865. 
Distr.—Fossil, 7 sp. Carboniferous; Michigan, Belgium, 
Nassau. P. glaber, Hall (cxxxii, 6). Probably others referred 
to Avicula, Pterinea, and more especially to Aviculopecten, 
Amussium and Pecten. 
Shell subequivalve, inequilateral, auriculated; hinge-line 
straight, with a central triangular cartilage-pit and a transverse 
plate, with smaller lateral cartilage-pits diminishing in size and 
depth from the centre outwards. 
