CARBONIFEROUS FOSSILS OF IRELAND. 25 



BeLLEROPHON EETICULATUS. M'^Coy. (PI. II. fig. 2). 



Sp. Ch. — Orbicular, compressed, umbilicus deep, rounded at the edges ; keel obtuse, rounded ; surface reti- 

 culated by equal spiral and curved transverse stria, forming small tubercles at the intersections. 



I have taken Professor Phillips' authority (Geol. York) for the axis of the B. decussatus of Fleming being 

 solid, which, therefore, differs from the present species, which is distinctly umbilicate ; the transverse striae are 

 also more obtuse in the present shell, and are equal in thickness to the spiral ridges. By this latter character 

 fragments of the two species may be distinguished. Diameter throe lines, thickness two and a half lines. 



Bellerophon tangentialis. Phil. 



Belleroplion tangentialis. Phil. Geol. York. 



Sp. Ch. — Central band sharp, narrow, prominent ; surface with transverse strife, which form tangents to 

 the umbilicus, and are perpendicular to the keel. 



The band of this species forms a compressed, prominent keel, and is distinguished from the other species 

 by the transverse stria; being perpendicular to it (in the others they meet it at a more or less acute angle), 

 and by their forming tangents to the edge of the umbilicus, which is large and rounded. Diameter one inch 

 two lines, thickness one inch. 



Bellerophon tenuifascia. Sow. 



Conch, naut. bMcus, var. c. Martin, Pet. Derb Bellerophon tenuifascia. Sow. MLn. Con. — Bellerophon tenuifascia. 



Phil. Geol. York. 

 Sp. Ch. — Band very narrow, elevated, threadHke; transverse striae very fine; umbilicus moderate. 

 The fineness of the transverse striae, and the very small, threadlike band, distinguish this from any other 

 of the genus ; the umbilicus is rather large and rounded. Diameter one inch seven fines, thickness two 

 inches. 



Bellerophon Wenlockensis. Sow. {?) 



Bellerophon Wenlockensis. Phil. Pal. Fos. 



A single cast of a small specimen, apparently of this species, has occurred. It is almost impossible, how- 

 ever, to identify internal casts of this genus with specimens in a perfect state. I have given this reference for the 

 Irish specimen, rather because it agrees perfectly with the small Devonian cast which Professor Philfips provi- 

 sionally placed with this species, than from a conviction that it is identical with the Silurian shell. 



Euphemus. M' Coy''. 



Gen. Ch. — Globose, involute, monothalamous ; surface spirally striated ; no dorsal band. 



Under this name I have separated those beautiful Httle shells hitherto ranked with Bellerophon, but desti- 

 tute of the dorsal band or keel characteristic of that genus ; the sculpturing of the surface of the two genera is so 

 distinct, that even fragments of them can in general be discriminated ; the striae or furrows on the surface of 

 Bellerophon are invariably transverse or parallel with the edge of the lip, while in Euphemus they are always 

 spiral, following the cfirection of the whorls ; a few reticulated species seem to imite the groups, which, taken 

 on the whole, are distinct. 



They are all of much smaller size than the true Bellerophons. 



* One of the Argonauts. 

 G 



