CARBONIFEROUS FOSSILS OF IRELAND. 59 



This species is allied to the P. minax, Phil., but is distinguished by its more gibbous, and smooth, convex, 

 anterior end. The anterior keel of this shell is interesting from its small size. Length from the beak to the 

 opposite margin seven lines. 



Pleurorynchus minax. Phil. 



Pleurorynchus minax. Phil. Geol. York Pleurorynchus minax. Phil, Pal. Fos Cardium aliforme. Var. Gold. Pet. 



Sp. Ch. — Heart-sliaped, gibbous; anterior side with a large, concave, central space; posterior side rather 

 short, rounded ; shell marked with nearly equal ribs, radiating from the beak, those within the concave anterior 

 space much finer than the rest. 



There appears to be much objection on the part of both British and foreign authors to admitting this as a 

 species distinct from the Cardium aliforme of Sowerby ; it is, however, easily distinguishable by the concave 

 space in the anterior side, with its enclosed ribs, which arc not more than half the thickness of those on any 

 other part of the shell. Length nine lines, width one inch nine lines. 



Pleurorynchus nodulosus. M-Coy. (PI. IX. fig. 4). 



Sp. Ch. — Conoidal; anterior face subtruncate, cordate; posterior side elongated; anterior keel obtuse, 

 nodulous ; surface with obsolete, longitudinal, antl transverse, obtusely rounded ridges. 



This small species is easily recognized by the keel which bounds the anterior face, being obtusely tuber- 

 culated or nodulous. Length three and a half lines, width (not including the anterior tube) about three lines. 



Pleurorynchus trigonalis. Phil. 



Pleurorynchus trigonalis. Phil. Geol. York. 



This species diiFers almost solely from the P. Hibernicus in having the posterior side much shorter, or, if 

 placed resting on its anterior face, it would be said to be more depressed. Length one inch four lines. 



Cypricardia alata. M'Coy. (PI. X. fig. 4). 



Sp. Ch. — Transversely trigonal, diagonally gibbous, beaks small, curved, prominent; anterior side narrow, 

 rounded ; a slight sinus in front ; posterior side dilated into a flat, rectangular wing ; hinge-line as long as the 

 shell is wide. 



This species is imlike any other of the genus with which I am acquainted: it forms a passage to Avicula. 

 Length five lines, width eight lines. 



Cypricardia concinna. M'Coy. (PI. VIII. fig. 24). 



Sp. Ch. — Transversely oblong, twice and a half as wide as long, diagonally gibbous; beaks moderate, 

 close to the anterior end ; anterior end very short, rounded, tumid ; posterior side lengthened, equally broad 

 throughout, abruptly truncated at the end ; a strong, rounded ridge extends from the beak to the posterior- 

 inferior angle ; surface sharply striated, parallel to the margin. 



This little shell is remarkable for Its great transverse length, and the abrupt or rectangular termination of 

 the posterior end, the points of the angles being rounded. Length one and a half lines, width four Hnes. 



Cypricardia cuneata. M'Coy. (PI. VIII. fig. 25). 

 <^. Ch. — Transversely oblong, rather more than twice as wide as long ; very gibbous, especially towards 

 the anterior side and beaks, which are very large and tumid ; anterior side very short, rounded ; posterior side 



