90 CABBONIFEKOUS LAMELLIBRANCHIATA. 



Moor, Yorkshire ; Castleton, Derbyshire. Ireland : the Carboniferous Limestone 

 of Little Island and Cork, co. Cork ; Lisnapaste, Ballintra, co. Donegal. 



Observations. — The type of P. incrassatus, M'Coy, is preserved in the Griffith 

 Collection, Museum of Science and Art, Dublin, and is a fine example of the left 

 valve of a full-grown shell (PI. XVI, fig. 15). This species belongs to a group 

 with large ears, which are almost smooth, and have no radiating ridges. The right 

 valve is flatter than the left valve, but has an almost identical ornament, the right 

 anterior ear being divided from the valve by a slit for the byssus. 



M'Coy unknowingly described this species under two names, for in 1855 he 

 referred specimens in the Woodwardian Museum to P. illegalis, de Koninck, while 

 assigning Pecten plicatus, of Phillips vec Sowerby, to this species. De Koninck 

 had made the same mistake in 1842 ; but he termed the shell Pecten Pliillipsianiis, 

 subsequently corrected to P. illegalis, neither of which names is mentioned in his 

 later work. 



It seems to me that the species is most frequently found in collections named 

 A. megalotis, M'Coy. The latter species was founded on a small fragment, showing 

 the posterior ear and a small portion of the adjacent part of the valve. Its ribs 

 were not nearly as coarse as those of A. incrassatus, and in my opinion the shell 

 was much too fragmentary for the foundation of a species. A second figure was 

 given, but this is not from any shell in the collection, and was probably a restora- 

 tion. At any rate, the name P. incrassatus appears in M'Coy's work before that 

 of P. megalotis, and therefore has the right of priority. 



AvicuLOPECTEN nobilis, de KonincJc, sp., 1842. Plate XVI, figs. 1 — G. 



Pecten nobilis, de KonincJc, 1842. Descr. Anim. Foss. Belg\, p. 132, pi. iii, 



fig. 24. 

 cancellatulus, M'Coy, 1844. Synops. Carb. Foss. Ireland, p. 89, pi. xiv, 



fig. 9. 

 ^qualis, M'Coy, 1844. Ibid., p. 89, pi. xv, fig. 13. 

 cognatus, M'Coy, 1844. Ibid., p. 90, pi. xix, fig. 4. 

 AvicuLorECTEN cancellatulus, M'Coy, 1855. Brit. Pal. Foss., p. 483, pi. 3 e, fig. 3. 

 nobilis, de KonincJc, 1885. Ann. Mus. Roy. d'Hist, Nat. Belg., 

 torn, xi, p. 217, pi. xxxvi, figs. 27, 28, 30. 



Specific Characters. — Shell small, triangularly suborbicular, inequilateral, the 

 left valve slightly more convex than the right valve. The margin of the valve 

 regularly rounded. The hinge-line straight, prolonged only slightly backwards. 

 The anterior ears moderately large, depressed, well marked off from the body of 

 the valve, the anterior margin falcate ; the posterior ears gently compressed and 

 expanded, also falcate. The umbones triangular, pointed and swollen, slightly 

 raised, subcentral. 



