CARBONIFEROUS FOSSILS OF IRELAND. HO 



LsPTiENA CONVOLUTA. Phil. 

 Lcptsena convoluta. Phil. Pal. Fos. 

 Sp, Ch. — Transversely fusiform, gibbous, convoluted; ears conical; surface with coarse, longitudinal, 

 rounded strias. 



A rare species, easily distinguished from the L. volva, M'Coy, by the coarse, direct striag of the surface. I 

 am not aware whether spines have been detected on the hinge-line ; the L-ish specimens do not shew any. 



Lept^na crassistria. M'Coy. (PI. XX. fig. 10). 



Sp. Ch. — Semicircular, convex; length two-thirds the width; beak large, gibbous; surface with about 

 twenty-eight coarse, roimdcd, radiating ridges ; ears smooth, flattened ; hinge-line spinous. 



This well-marked species is very abundant in certain localities. The radiating ribs are sharp, equal, 

 rounded, and about equal in width to the spaces between them ; the ears are smooth, and much flattened ; 

 there are about twelve short, slender, cixrved spines on the hinge-line. Length five and a half lines, width 

 seven and a half lines. 



Lept^na Dalmaniana. Kon. 



Sp. Ch. — Semicircidar, flat, nearly twice as wide as long; surface covered with very fine, flexuous stria; 

 ten or twelve slender spines on the hinge-fine. 



The strise on this beautiful species are so fine, as to be indistinctly seen with the naked eye ; they are 

 flexuous ; the substance of the shell is very thin, and both valves are perfectly flat ; the spines on the hinge- 

 line are short and slender. Length eight lines, width thirteen lines. Before receiving De Koninck's work I 

 had figured this species, PI. XX. fig. 7. 



Lept^na gibberula. M'Coy. (PL XX. fig. 11). 



Sp. Ch. — Semicircular, length two-thirds the width, very gibbous in the middle ; ears acute, flattened; 

 surface very finely and regularly striated longitudinally. 



This curious little species is not uncommon in the carb. slate series of Ireland, the shales of which abound 

 with small species of Orthis and Leptmia, from all of which the present is distinguished by the great gibbosity 

 of the middle portion, or body of the shell, the flattened, acute ears, and the nearly smooth surface, the longi- 

 tudinal striae being so fine as to require the lens to render them distinctly visible ; they are close, rounded, and 

 perfectly equal, in which they difier from the Silurian L. sericea, Sow., with one of the varieties of which it is 

 likely to be confounded. Length one and a half lines, width three lines. 



Lept^na Hardrensis. Phil. sp. 



Orthis Hardrensis. Phil. Pal. Fos. 



Sp. Ch. — Semicircular, one valve convex, the other slightly concave; hinge-line equal to the width of the 

 shell, armed with ten short, cylindrical spines ; surface strongly striated from the beak ; striffi crossed by minute, 

 transverse lines ; internal surface rough, with small, depressed spines ; impressions large, renlform. 



It closely resembles the L. lata of the Silurian rocks. The L. sarcinulata of continental authors seems to 

 include them both. 



Lept^na lata. De Buch. {?) 



Leptaena lata. (?) Sow. Sil. Syst. 

 A few fragments of a Leptana, possibly of this species, have occurred very rarely, but it is possible they 

 might be referred to some of the varieties of the preceding species. 



