PAL^EOLIMA SIMPLEX. 39 



radiating ribs and sulci. A deep groove between the umbones in each valve for 

 the cartilage or ligament. 



Observations. — This genus has been erected for shells which have somewhat the 

 external form of Limn, but evidently differ from this genus in some details. So 

 far as the hinge can be observed there are no hinge-teeth, and a strong ligament, 

 which is external and lodged in a comparatively deep and broad groove, is therefore 

 necessary. Three species are now referred to Palseolima. 



Paljsolima simplex, Phillips, sp., 1836. M'Goy, emend. 1844. Plate XIX, figs. 



24—27. 



? Pecten simplex, Phillips, 1836. Geol. Yorks., pt. ii, p. 212, pi. vi, fig. 27. 

 Avicula simplex, cle Koninck (pars), 1843. Descr. Aniin. Foss. Belg., p. 137, 



pi. iv, fig. 2. 

 Pecten simplex, M'Coij, 1844. Synops. Carb. Foss. Ireland, p. 100. 

 ? Aviculopecten dupliciradiatus, de KonincJc, 1885. Ami. Mus. Roy. d'Hist. Nat. 



Belg., torn, xi, p. 239, pi. xxxiv, fig. 1. 

 cf. Limatulina radula, de Koninck, 1885. Ibid., p. 24G, pi. xxxvi, fig. 15. 



Specific Characters. — Shell small, almost equivalve, oblique, triangularly ovate, 

 gibbose. The anterior border nearly straight, the lower margin curved, the 

 posterior oblique and almost straight. The hinge-line very short, the umbones 

 gibbose, pointed, incurved, slightly raised, and almost central. The ears small and 

 depressed, not well defined, the posterior very small. A few obscure concentric 

 lines of growth. 



Interior. — Unknown. 



Exterior. — The surface is ornamented with several broad, bifurcating, unequal, 

 radiating ribs, the anterior ribs flattened, the posterior ribs angular. Ears smooth. 



Dimensions. — PL XIX, fig. 24-, a right valve from Poolvash, measures — 

 Antero-posteriorly .... 20 nun. 



Dorso-ventrally . . . .20 mm. 



Localities. — England: the Carboniferous Limestone of Settle; above Hardraw 

 Scar Limestone, Millgill Asgrigg, Yorkshire. Isle of Man : Carboniferous Lime- 

 stone, Poolvash. Scotland : the Carboniferous Limestone series, Teasses, Largo ; 

 Burn at Craigdouffie, Kilsyth ; Glen Hind og Dairy. Ireland : the Carboniferous 

 Limestone, Little Island, co. Cork. 



Observations. — The type of Phillips's Pecten simplex has disappeared, and the 

 description and figure are very meagre and poor. M'Coy, however, gave a better 

 description, from which the shell is fairly easily recognised ; but he describes the 

 right valve as "nearly flat," a statement I cannot accept, the right being only a 

 little less gibbose than the left valve. 



