PECTEN asper. 
TAB, CCCLXX. — Fig. 1. 
Spec. Char. Nearly orbicular, convex on 
both sides, bearing' about 17 sets of rays 
roughened by subtubular imbricated scales ; 
margin internally fimbriato-crenated ; ears 
distinct, nearly equal. 
Syn. Pecten asper. Lamarck Hist. Nat. VI. 
180. Lister Conch . t. 470. f. 28. 
The rays are from 5 to 7 in a set, depending upon the 
age of the shell ; the centre of each set has the largest 
scales, and is much elevated ; the contour is oblique, 
much resembling that of the common P. opercularis. 
The inside is plain with a furbelowed margin. 
Very abundant in the Green Sand, especially at Horn- 
ingsham near Fro me, Lamark describes P. asper as 
having 20 to 22 rays ; this is not the case in the English 
specimens. 
PECTEN obliquus. 
TAB. CCCLXX— Fig. 2. 
Spec. Char. Obliquely oval, convex on both 
sides ; radii very numerous, roughened by 
semicircular imbricated scales ; ears large, 
distinct. 
Every third ray is larger than the two intermediate 
ones, they are all close together, the larger amount to 
about 20. The two valves are not equally convex, but 
otherways they are similar ; the breadth it about two- 
thirds the length. 
Drawn many years ago from a specimen in green 
sand belonging to my lamented friend Mr. Cunnington, 
