80 CARBONIFEROUS LAMELLIBRANCHIATA. 



Aviculopecten Losseni, von Koenen, sp., 1870. Plate XVIII, figs. 1, 2. 



Pecten Losseni, von Koenen, 1879. Neues Jahrb. f. Min., p. 328, pi. vi, 



figs. 1 a — d. 



Specific Characters. —Shell of very moderate size, triangularly ovate, almost 

 equilateral. The anterior and posterior borders very oblique and nearly straight, 

 the inferior border broadly rounded. The hinge-line short. The ears triangular, 

 well marked off from the valve, produced and pointed along the upper border, the 

 margins falcate ; the posterior larger than the anterior ear. The umbones small, 

 pointed, and incurved. 



In terior. — Unknown. 



Exterior. — The right valve is marked with concentric lines and striaa of growth ; 

 the ears possessing few but well-marked radiating ribs, decussated by concentric 

 lines of growth. The left valve is ornamented with numerous close, fine, distinct, 

 radiating ribs, new ones arising between each original pair as they pass over the 

 shell. The ribs are crossed by fine concentric lines and striae of growth. Ears 

 with radiating ribs, fewer and wider apart in the posterior ear. 



Dimensions. — PL XVIII, fig. 1, a crushed specimen from Angram Brook, 

 measures — 



Antero-posteriorly . . . .27 mm. 



Dorso-ventrally . . . .27 mm. 



This would be probably much narrower in a normally gibbose specimen. 



Localities. — The Pendleside series of Angram Brook, Pendle Hill, Lancashire. 



Observations. — Unfortunately all my examples of this species are crushed fiat in 

 a shaly matrix, but I have no hesitation in referring them to A. Losseni of von 

 Koenen, who gives excellent figures of this species. 



I have been able to make out that the right valve has no radiating ribs, for in 

 two specimens the valves have been crushed on each other. 



Von Koenen refers P. lineatns, Sarres, to his species, which he considers to be 

 distinct from V. lineatus, Groldfuss. I have no knowledge of the original shells of 

 these authors, and am therefore unable to advance any opinion on the question of 

 the synonymy of the species. 



I think the species should he placed in the genus Aviculopecten, to the other 

 speeies of wliich it lias a general resemblance. 



A. Losseni is another shell common to the Pendleside series of England and the 

 Culm of the European continent. 



