FROM THE TERTIARY OF VIRGINIA. 245 
This little shell is interesting from its singular spinous appendages. No other Mo- 
diola, that I have met with, has them. Indeed, the only shell I have ever seen with 
spines similarly posited, is the Cardium aviculare, Lam., from the Paris Basin. 
FAMILY MALLEIDA. 
GENUS AVICULA. 
A. MULTANGULA, Pi. 35. Fic. 31. 
A. testé valde transversd, sub-inequilaterali, anticé acute rostrata, posticé truncata, compressd, undutatd, crassd, striatd; 
striis radiantibus minimis, raris; clivo umboniali elevato; margine basali flecwoso; margine dorsali recto; natibus compressis; 
cardinis ared triangulari, transversd; sulco ligamentifero, triangulari, profundo; teste parte anticd interné valde incrassatd. 
Shell very transverse, sub-inequilateral, acutely rostrate anteriorly, truncate posteriorly, compressed, undulate, 
thick, striate; strim few, radiating, very small; umbonial slope elevated; basal margin flexuose; dorsal margin straight; 
beaks compressed; area of the beaks triangular, transverse; ligamentiferous sulcation triangular, deep; anterior part 
of the shell, very much incrassated within. 
Diam. .18. Length .20. Breadth .45 of an inch. 
Remarks.—There are numerous exceedingly minute lines of growth over the surface. 
The radiating stria are plainest where they terminate at an angle in the basal margin. 
The cavity of the beaks is very deep and small. It is abruptly cut off by the incrassa- 
tion of the anterior end, which is perfectly flat and on a level with the dorsal and basal 
margins. As all of my specimens are very much worn, I cannot perceive any trace of 
the muscular impressions. 
This curious little shell differs from the genus Avicula somewhat in the hinge. The 
fosset is more conspicuous than in general with that genus, while the tooth is almost or 
entirely obsolete. I had at first intended erecting a new genus for it, but the characters 
of the hinge in this family are so variable and s0 little to be depended on, that I have 
thought it best to leave it in this genus. It can hardly be confounded with any of its 
congeners, 
FAMILY PECTENIDA:, 
GENUS PECTEN. 
€ « 
P. micropLEuRA, Px. 35, Fie, 32. 
P. test longitudinaliter ovata, sub-inflatd, crassa, radiatim costatd; costis parvis, crebris, regularibus, planis, levibus; 
margine basali circulari; auribus equalibus, costatis; natibus compressis, aculrs. 
Shell longitudinally ovate, somewhat inflated, thick, radiately costate ; coste small, numerous, regular, flat, smooth; 
basal margin circular; auricles equal, costate; beaks compressed, acute, 
Diam. .30, Length .60, Breadth .58 of an inch. 
Remarks.—The whole surface, from one auricle to the other, is covered with small, 
regular, smooth ribs, distant from each other about their own width. They are between 
thirty and forty in number, besides about ten on each auricle. 
VOL. IX.—65 
