04 CARBONIFEROUS LAMELLIBRANCHIATA. 



Dimensions. — PI. XII, fig. 13, a right valve from Settle, in the York Museum, 

 measures — 



Antero-posteriorly . . .53 mm. estimated. 



Dorso-ventrally . . . .53 mm. 



A bivalved example of almost the same size measures 18 mm. from side 

 to side. 



Localities. — England : the Carboniferous Limestone of Settle, Yorkshire ; 

 Castleton, Derbyshire ; Narrowdale and Wetton, Staffordshire. 



Observations. — The type of Pecten : fimbriates, Phillips, is unfortunately missing, 

 but the figure is good, and the description, though meagre, is sufficiently detailed 

 for the identification of the species. The original description is as follows : — 

 " Oblong, depressed, with small plain ears ; surface radiated with obtuse ribs and 

 furrows, all sinuoso-imbricate." Apparently a left valve was figured. The right 

 valve differs very little, both in convexity and ornament, from the left valve. 

 PI. XII, fig. 12, represents a semi-decorticated specimen of a bivalved example. A 

 small patch of the outer shell remains on the left valve. The specimen is figured 

 to show how easily a shell in this condition might be referred to an entirely 

 different species. 



The ornament on the right valve of A. dissimilis, Flem., sp., resembles somewhat 

 that of A. fimbriates, but the shape of the valve and the ears are quite different. 

 The locality given for the type specimen is Castleton, probably Derbyshire. 



A fine right valve in the York Museum is figured (PI. XII, fig. 13), and this 

 is almost entire, only the anterior ear being wanting. 



Aviculopeoten iNTEUSTiTiALis, Phillips, sp., 1836. Plate XIV, figs. 16 — 21. 



Pecten intekstitialis, Phillips, 1836. Geol. Yorks., pt. ii, p. 212, pi. vi, fig. 24. 



— segeegatus, M'Coy, 1844. Syuops. Carb. Foss. Ireland, p. 99, pi. xvii, 



fig. 3. 

 Kokchakofi, de Verneuil, 1845. Geol. Russie de l'Europe, p. 325, pi. xx, 

 fig. 16. 



— Bouei, de Verneuil, 1845. Ibid, p. 326, pi. xxi, fig. 6. 

 Aviculopecten segregatus, M'Coy, 1855. Brit. Pal. Foss., p. 489, pi. 3 e, li,^'. 1. 

 Limatulina selecta, de Koninck, 1885. Aim. Mus. Roy. d'Hist. Nat. Belg., 



torn, xi, p. 244, pi. xxxvi, figs. 1—5. 

 Non Avicttlopecteh interstitialis, de Koninck, 1885. Ibid., p. 227, pi. xxxiii, fig. 21. 

 Bouei, de Koninch, 1885. Ibid, p. 220, pi. xxxv, figs. 8, 9. 



Specific Characters. — Shell below medium size, longitudinally and obliquely 

 subtrigonal, with sharply defined, depressed cars; the loft valve gibbose, the right 



