CARBONIFEROUS FOSSILS OF IRELAND. 



Inoceramus. Sow. 



Gen. Ch — Shell thick, inequivalve, triangular, deep ; umboncs incurved, lateral; hinge short, formed of 

 a scries of transverse grooves. 



&' 



Inoceramus AUEicuLATUS. M'Coy. (PI. XIX. fig. 5). 



Sp. Ch. — Longitudinally oval, gibbous; beaks nearly central ; posterior side expanded, compressed, slightly 

 oblique; anterior side with a large, square car, deeply divided from the body of the shell ; surface smooth at 

 the sides, marked with broad, obtusely rounded, concentric wrinkles in the middle. 



This species is distinguished from the /. vehistiis by the large ear on the anterior side, and nearly direct 

 hinge-line ; it is also less oblique. Length eleven lines, width nine lines, length of hinge-line five lines. The 

 specimen figured was kindly lent by Dr. Haines of Cork. 



Inoceramus l^evissimus. M'Coy. (PI. XIX. fig. 6). 



Sp. Ch. — Longitudinally oval, compressed, gibbous in the middle; anterior side compressed, produced 

 above the beaks into a short, angular wing ; beaks small ; a lengthened oblique lunette on the posterior side of 

 the beaks; siu'face perfectly smooth. 



This elegant shell most nearly resembles Count Miinster's I. inversus of the Eifel, from which it diifers in 

 being much more compressed, the middle alone being convex ; in its greater length, very small beaks, and per- 

 fectly smooth surface. Length two inches eight lines, width one inch ten lines. The specimen was presented 

 by Mr. Jennings of Cork. 



Inoceramus ORBICULARIS. M'Coy. (Pl.XIII.fig.il). 



Sp. Ch. — Orbicular, convex, hinge-line oblique; surface with about fifteen broad, smooth, concentric ribs ; 

 length and width equal. 



The almost perfectly orbicular form, and regular, concentric, flattened ribs, distinguish this from any species 

 of the genus with which I am acquainted ; the hinge-line is rather long, oblique ; beak one-third the length from 

 the anterior end ; the convexity is much less than in most others of the genus. Length eleven lines, width 

 twelve lines. 



Inoceramus vetustus. Sow. 



Inoceramus vetustus. Sow. Min. Con. — Inoceramus vetustus. Phil. Geol. York Posidonia vetusta. Koninck. Fos. Bel. 



Sp. Ch. — Ovate, convex; beaks short, pointed, curved; hinge-line short; surface smooth, with about four- 

 teen large, prominent, concentric undulations. 



This species appears to belong to the chalk genus Inoceramus, rather than to the PosidonicB. Length one 

 inch nine lines, width one inch four lines. 



Posidonia. Gold. 



Posidonomya. Bronn. 



Gew. O.— Obliquely ovate, tliin, compressed, concentrically ridged ; hinge-line oblique, subauriculated 

 on each side ; beaks subcentral. 



It seems exceedingly probable, as M. Deshayes has already suggested, that Posidonia may be the inter- 

 nal plate of an animal allied to Aphjsia. I was particularly struck with the resemblance while dissecting 

 some large specimens of the Aplysia depilans of our coast this summer : the gill covers of those animals, when 

 observed in the recent state, or before being dried, are precisely similar to a Posidonia in shape, and with 

 somewhat similar concentric wrinkles, but more faintly marked ; their consistence is intermediate between that 



u 



