CONCHIFERA. 
PERNOPECTEN, Winchell, 1865. 
Derivation, Perna and Pecten, from a combination of some of 
the characters of the two genera. 
Type, Aviculopecten limzeformis, White and Whitfield. 
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. 
Pernopecten agrees with Amusium in its subsymmetrical ears, 
cardinal cartilage pit, and in the absence of radiating ridges, 
but differs in its straight hinge line and lateral cartilage pita. 
Fossil, 7 species. Carboniferous limestone. Michigan, Bel- 
gium, Nassau. Probably others referred to Avicula, Pterinea, 
and more especially to Aviculopecten, Amusiwm, and Pecten. 
AYVICULOPECTEN (p. 417) does not possess the prismatic of the 
Aviculide, but the peculiar corrugated tubular structure of the 
Pectinidee (Meek). It bears the same relations to existing 
Pectens as Pterinea does to existing Avivulas. 
PLICATULA (see p. 414). 
Sub-genus, Harpaw (Parkinson, 1811), Deslongchamps, 1858. 
Example, Harpax Parkinsoni, Brown. 
Hinge of attached valve consisting of a flattened triangular 
plate, traversed by a central more or less perpendicular liga- 
mental furrow, exterior to which are slightly marked diverging 
sulci to receive the elevated borders of the ligamental groove 
in the other valve; the outer borders of the plate form length- 
ened and eleyated dental processes. Hinge plate of free valve 
traversed mesially by the ligamental groove, the borders to 
which are elevated and but slightly diverging; exterior to — 
these are strongly impressed grooves to receive the dental pro- 
cesses of the other valve. 
Fossil, 16 species. Lias and Lower Oolites. France and 
England. 
TERQUEMIA, Tate, 1867. 
Dedicated to M. O. Terquem, an eminent palzeontologist. 
Example, T. Heberti, Terquem, Mem. Soc. Géol. de Fr., vol. 
viii. p. 106, t. 13, f. 1—3, 1865. 
Synonym, Carpenteria, EH. Deslongchamps, 1858 (non Gray, 
1856. 
Shell inequivalye, subequilateral, attached by the umbonal 
portion of the right valve; the left valve slightly concave, 
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