CARBONIFEROUS FOSSILS OF IRELAND. 45 



In July, 1841, I published a description ol'tliis species in a catalogue wliicli I wi'ote of my friend, the late 

 Major Sirr's fossils, who had collected the specimens from the Klldare limestone. The following year Viscount 

 D'Archiac and M. de Verncuil published a description of a fossil from the greywacke of Kemmenau, which 

 seems identical, although much less compressed. 



ACROCULIA SIGMOID ALLS. PllU. 



Acroculia sigmoidalis. Phil. Pal. Fos. 

 A small fragment of this species, unfit for description, has occurred. 



Acroculia triloba. Phil. sp. 



Pileopsis triloba. Phil. Geol. York. 

 Sp. Ch. — Compressed, conical, arched; apex free, deflected, obtusely pointed ; aperture distinctly trilobate, 

 surface marked with lines of growth parallel to the margin, otherwise smooth. 



This remarkable species is known from the A. vetusta by its more compressed form and free apex. 



Acroculia tubifer. Sow. sp. 



Pileopsis tubifer. SO10. Min. Con. — Pileopsis tubifer. Phil. Geol. York. 



Sp. Ch. — Conical, acvite, apex obtuse, not incurved ; three obscure, longitudinal undulations in the front; 

 each bearing a row of long tubular spines. 



This species is much more lengthened and narrow than any of the others ; the apex is arched, but not dis- 

 tinctly incurve at any stage of growth ; the three rows of tubular spines are very remarkable. Length eleven 

 lines, diameter of the mouth six lines. 



Acroculia vetusta. Phil. 



Pileopsis vetusta. Sow. Min. Con. — Pileopsis vetusta. Phil. Geol. York — Acroculia vetusta. Phil. Pal. Fos. 



Sp. C/«.— Shell obliquely conical, gibbous; spire enrolled ; mouth nearly circular in young, but lengthened 

 in old individuals. 



Much doubt has arisen as to what shell was intended by Sowerby for his Pileopsis vetusta, every subse- 

 quent writer quoting his figure with a mark of doubt, the shells which most usually occur not presenting the 

 compressed form, lengthened aperture, or longitudinally undulated surface of Mr. Sowerby's larger figure, but 

 agreeing perfectly with his smaller one ; hence the question has arisen, whether Mr. Sowerby has confounded 

 two species of Pileopsis, and which of them has the best right to the specific name vetusta. It appears that 

 young specimens have the mouth almost circular ; the surface smooth or obscurely wrinkled transversely, and 

 the whole shell having a gibbose or inflated appearance ; the beak delicate, acute, and incurved, in this state 

 agreeing perfectly with Sowerby's 2 and 3 in the Mineral Conchology, Professor Phillips's figures in the 

 Geology of Yorkshire, l-'alsozoic Fossils, &c. ; by age, however, the sides become compressed ; the back narrow, 

 flattened, and bounded on each side by an irregularly rounded ridge or undulation, the beak becomes blunt, the 

 mouth lengthened, and the lip undulating. Length of an old individual two inches four lines ; length of the 

 aperture one inch nine lines ; width one inch three lines. 



Patella. Linn. 

 Gen. Ch. — Conical, depressed; apex inclined to the anterior side; aperture oval; muscular impression in- 

 terrupted at the head of the animal ; surface radiatingly striated. 



M 



