88 CARBONIFEROUS LAMBLLIBRANCHIATA. 



figure. The right valve is stated by him to be unknown, and I have not been able 

 to identify it. The small ears and circular shape, with the numerous radiating 

 ribs, are characters which serve to distinguish the species. 



AVICULOPECTEN STELLABIS, Phillips, sp., 1836. Plate XVI, figs. 7 — 11. 



Pecten stellabis, Phillips, 1836. Geol. Yorks., vol. ii, p. 212, pi. vi, fig. 18. 

 — villanus, de Koninch, 1851. Descr. Anim. Foss. Belg., App., p. 684, 

 pi. lvii, fig. 4. 

 Aviculopecten villanus, de Koninch, 1885. Ann. Mus. Roy. d'Hist. Nat. Belg., 

 torn, xi, p. 218, pi. xxxiii, figs. 7, 8 ; pi. xxxiv, fig. 22. 

 ingratus, de Koninch, 1885. Ibid., p. 224, pi. xxxv, figs 33, 34. 



Specific Characters. — Shell below medium size, quadrato-orbicular, the left 

 valve moderately gibbose, the right less so. The margin of the valve from ear to 

 ear regularly curved, almost circular. The hinge-line long, rolled, extending 

 almost as far forward as the anterior margin, and posteriorly somewhat beyond 

 the posterior margin. The umbo central as regards the body of the valve, gibbose 

 and pointed in the left valve, and not elevated. Anterior ears depressed, deeply 

 marked off from the rest of the valve by an angular groove ; the posterior ears 

 long and gradually compressed, falcate. 

 Interior. — Unknown. 



Exterior. — The convex surface of the left valve is adorned with simple, rounded, 

 radiating ribs, which may or may not have secondary ribs arising between each 

 pair as they approach the margin. The ribs are quite absent on the ears, which 

 are only concentrically striated by fine lines of growth. The body of the valve is 

 crossed by very fine concentric striae, one of which is sometimes fairly deep, making 

 the ribs along this lino imbricated. The sulci between the ribs are very finely 

 striated concentrically. 



. Dimensions. — PL XVI, fig. 8, a left valve from Castleton, measures — 

 Antero-posteriorly . . . .25 mm. 



Dorso-ventrally . . . .25 mm. 



Length of hinge-line . . . .27 mm. 



Convexity of valve . . . .7 mm. 



Localities. — England: the Carboniferous Limestone of Castleton and Park 

 Hill, Derbyshire; Hill Bolton and Settle, Yorkshire; above Main Limestone, Nine 

 Standards Rigg, Westmoreland; the White Limestone, Poolvash, Isle of Man. 

 Ireland : the Carboniferous Limestone of Little Island, co. Cork. 



Observations. — The type of Pecten stellaris, Phillips, is preserved in the 

 Gilbertson Collection, Natural History Museum, South Kensington. It is a left 



