154 ANATINIDA. 
radiately ? sometimes partially) striated or suleated. Only 
palzozoic species are referred to the genus ; some of them are in 
external form almost identical with Pharella, and it as yet 
remains to be shown whether there are in Sanguinolites any 
hinge-teeth or not. In the Brit. Pal. foss. |p. 276), M’Coy con- 
siders this genus apparently identical with King’s Allorisma, 
which is very doubtful. 
poMAcrus, Meek, 1871. Shell thin, more or less elongate- 
subtrapeziform, nearly or quite equivalve, either inequilateral 
or equilateral, the beaks being nearer the auterior or posterior 
end, or central, according to the species; valves closed all 
around, and each with a well-defined keel or more obtuse 
ridge extending from the posterior side of the beaks to the 
posterior basal extremity; anterior side attenuated and pro- 
duced; posterior margin wider (higher) than the other, and 
obliquely truncated ; dorsal margin sloping in front of the beaks, 
and more nearly horizontal and apparently without an escutcheon 
behind them ; ligament external or marginal, rather long ; surface 
with concentric lines and ridges, and sometimes obscure radiating 
markings on the umbonal region. Hinge, muscular, and pallial 
impressions unknown. P.nasutus, Meek. 2 sp. Carb.; Missouri. 
Pyanomya, Miller, 1882. 
Distr.—P. gibbosa, Miller (exx, 9, 13). Hudson Riv. Group; 
Cincinnati, Ohio. 
Shell small, inequilateral, with thin, fragile, ventricose, edentu- 
lous valves, united by an external ligament ; no escutcheon. 
GrammysiA, de Verneuil, 1847- 
Disir.—Silur., Devon.; N. Am., Eur. G. pes-anseris, Sandb. 
(cxx, 14). G. ovata, Sandb. (exxi, 5). 
Shell equivalve, inequilateral, transverse; not gaping; mus- 
cular impressions very unequal; pallial line posteriorly rounded, 
bordering the large muscular impression so as to leave the latter 
two-thirds without it; ligament exterior, prolonged, in a depres- 
sion of the dorsal line; surface with one or more oblique ribs, 
and several rounded concentric plications. 
OrtHonota, Conrad, 1841. 
Distr.—O. undulata, Conr. O.contracta, Conr. (cxxix, 13,14). 
Suess as. 
Shel! narrow, with subparallel upper and lower margins, very 
inequilateral, the beaks being subanterior and tumescent, lunula 
in front of the beaks somewhat excavated, very thin, surface pos- 
teriorly generally undulately striated, hinge apparently without 
teeth. 
