LAMELLIBRANCHIATA. | UPPER PALZZOZOIC MOLLUSCA. 477 
PECTEN? FIMBRIATUS (Phill.). 
Ref. = Pecten fimbriatus Geol. York, t. 6. f. 28. 
Desc.—Ovate ; valves slightly and almost equally convex, apical angle 90°; ears large, anterior left one 
square, extending as far as the edge of the shell, with coarse imbricating strie parallel with the end; anterior 
ear of right valve long, narrow, subtruncate at the end, and with a very deep narrow notch between it and 
the body of the shell, having three or four obscure radiating ridges crossed by imbricating strie of growth ; 
posterior ears very short, obtuse. Surface of each valve radiated with a variable number of obscurely marked 
obtuse ridges, crossed by close, minute, obsolete, scalloped strize, strengthened, at intervals of about half a line 
to one line apart, into fine imbricating lamellar lines of growth, scalloped between the ridges which they cross. 
Width from beak to opposite margin one inch eight lines, proportional length at right angles thereto “, length 
of anterior ear 4, posterior ears about =. 
There is considerable variety both in the strength and number of the radiating ridges of this beautiful 
species; from four to eight being the extremes of number I have seen (about the middle of the shell) in a space 
of three lines, the former in a left, the latter in a right valve. 
Position and Locality—Common in the dark argillaceous carboniferous limestone of Lowick, Northum- 
berland. 
PECTEN PUSILLUS (Schlotheim). 
Ref. and Syn. = Discites id. Schlot. Akad. Miinchen, Vol. VI. t. 6. f. 6, = Pecten id. King, Perm. 
Foss. t. 13. f. 1, 2, 3 (too oblique). 
Desc.—Ovate, not oblique; valves of nearly equal depth, moderately and evenly convex ; greatest depth 
a little above the middle; beaks prominent; ventral margin semicircularly curved; sides converging to the 
beaks, straight, and forming narrow slopes nearly vertical to the plane of the margins, and deeply defining the 
ears on each side; posterior ear very small, nearly rectangular; anterior ear much longer, narrow, triangular, 
and separated by a deep narrow notch from the body of the shell in the right valve, nearly rectangular and 
confluent with the margin of the shell in the left valve. Surface smooth, with a few fine lines of growth near 
the edge, and sometimes shewing very faint obtuse radiations from the beak. Average width from beak to 
opposite margin five lines, proportional length at right angles thereto “, length of posterior ear “, of anterior 
ear =, depth of left valve =. 
From the anterior ear of this little species so obviously exceeding the posterior one in length, I have no 
doubt of this being a true Pecten, although I have not seen the cartilage pit. 
Position and Locality.—Common in the Permian limestone of Humbleton Hill. 
PECTEN SUBELONGATUS (JZ°Coy). 
Ref. and Syn. = Pecten elongatus M°Coy, Syn. Carb, Foss. t. 16. f. 9 (not of Lamark). 
Desc.—Regularly ovate; apical angle 100°; gently convex near the beak, gradually flattening towards 
the margins ; surface smooth or minutely striated concentrically ; ears nearly equal, small posterior one square, 
slightly defined, the anterior rather longer, with a few obsolete radiations, rounded, deeply separated from the 
body of the shell. Width from beak one inch six lines, proportional length at right angles thereto %, length of 
anterior ear =, of posterior ear 4, depth of left valve =. 
This fine species appears smooth to the naked eye, but in finely preserved specimens, or with the aid of a 
lens, very minute, regular, impressed, concentric strize are visible. From the P. Sowerbyi (M°Coy), which has 
somewhat similar strize, it is distinguished by its greater size and the form of its ears, while from the P. filatus 
(M°Coy), which to the eye appears nearly as smooth, and has the same general form, it is distinguished by 
having the minute striation concentric, instead of longitudinal, as in that species. 
Position and Locality.—Not rare in the dark carboniferous limestone of Lowick. The original Irish locality 
is Millicent, Kildare. 
