236 CARDINIIDA. 
usually but slightly prominent, sometimes obsolete ; lateral teeth 
more or less developed, often very thick ; muscular impressions 
simple, deep. (Entirely fossil.) 
Carpontcona, M’Coy, 1855. 
Distr.—20 sp. Carboniferous; Europe, United States. C. 
acuta, Sowb. (exxiv, 97). 
Shell elongated, solid, with moderately tumescent, not eroded, 
beaks, somewhat impressed in front of them; ligament strong, 
external; surface concentrically striated; hinge with one very 
thick cardinal tooth in the right valve, extending posteriorly, 
with one long anterior and one long posterior lateral tooth ; 
muscular sears one either side, each surmounted by a small 
accessory impression. 
AnTHRACcOSIA, King, 1856. 
Etym.—Anthraz, carbon, in allusion to the carboniferous de- 
posits in which the genus is usually found. 
Distr.—61 sp. Devonian—Carboniferous ; Westphalia, Sax- 
ony, Russia, Belgium, Great Britain, N. America. A. Loltnert, 
Ludwig (cxxv, 10). 
Shell equivalve, inequilateral. Teeth one in each valve below 
the umbone, rather low and massive; crown of tooth of right 
valve excavated anteriorly and ridged posteriorly; crown of 
tooth of left valve ridged anteriorly and sloped posteriorly. 
Umbonal ligamental fulcra each a furrow excavated in the hinge- 
plate, between the umbone and tooth; scars of the anterior set 
of pedal muscles, situated above the anterior adductor muscular 
impressions. 
Anthracosia differs from Unio, to which genus the majority of 
the Unioniform shells have been referred, in its simpler dental 
system and in the absence of supplementary pedal muscles. 
ANOPLOPHORA, Sandberger, 1862. 
Syn.—Unionites, Munst. Myacites, Auct. 
Distr.—Triassic. A. lettica, Quenst. (exxii, 37). 
Shell elongated, laterally moderately compressed, inequilateral, 
beaks subanterior, hinge with a small indentation, without any 
perceptible cardinal teeth and with very slightly thickened lateral 
margins on either side; anterior muscular impression cordiform, 
enlarged, posterior very faint, ligament linear, external. 
Most of the species referable to this genus occur in the Trias ; 
they differ from Cardinia by the want of hinge-teeth, and some 
forms closely resemble Pleurophorus, but they appear to have a 
thinner shell. 
