CARBONIFEROUS FOSSILS OF IRELAND 135 



Spirifera striata. Sow. 



Anomites striatus. Mart. Pet. Dcrb. — Spirifer striatus. Sow. Min. Con. 



Sp. Ch. — Semicircular, depressed; cardinal angles acute; mesial fold angular, produced in front; cardinal 

 area large, hollow, with parallel sides ; about fourteen sharp, unequal sulci on the mesial fold, and thirty-seven 

 on each side. 



Next to Spirifera princeps, M'Coy, and S. (jiganteiis, Sow., this is the largest of the known Spirifers, fre- 

 quently attaining the width of four inches, or even more. The surface is much depressed ; the mesial fold 

 strongly defined, angular, and forming a triangvilar projection in front; the sides are acutely angular; car- 

 dinal area large, and much cvu'ved ; the beak incurved, but small ; the stria3 are exceedingly numerous, sharply 

 defined, narrow, and rather unequal. This shell is very well known on the Continent, as the species in which 

 Mr. Sowerby first discovered the spiral appendages, a part of whicli he figured, rather larger than nature, in the 

 twelfth volume of the Transactions of the Linua3an Society. Length three inches, width four inches and a half, 

 depth one inch and a half. 



Spirifera TRANSiENS. M^Coy. (PL XIX. fig. 14). 



Sp. Ch. — Triangular, or rhomboidal, including the beak, twice as wide as long, gibbous; mesial fold very 

 large, prominent, rounded, undefined, producing a very deep sinus in the front margin ; sides radiated with 

 about ten or twelve large, thick, rounded ribs, equal, or irregularly duplicate ; mesial fold with about six or 

 seven ribs, equal in size to those of the sides ; cardinal angles acute ; cardinal area low, triangular. 



This species is most nearly allied to the S. fjrandceva of the Devonian rocks, but is distinguished by its 

 very large, undefined mesial fold, and more tumid sides ; from S. bisculcata and S. attenuata it differs in its 

 very large, undefined, mesial fold, and the smaller number and greater size cf its radiating ribs, and most im- 

 portantly by the triangular cardinal area, as in Cyrtia. Length one inch seven lines, width two inches six 

 lines. Young specimens are not so wide in proportion to the length. 



Spirifera trigonalis. Sow. 



Anomites trigonalis. Martin, Pet. Derb Spirifer trigonalis. Sow. Min. Con. 



Sp. Ch. — Gibbous; margin semicircular; cardinal angles acute; hinge-line broad, flat; from twenty 

 to thirty strong, radiating ribs, three of which are elevated to form the mesial ridge ; the ribs of the mesial fold 

 usually divide into two or three as they approach the margin, those of the sides always entire. 



They are, perhaps, two species confounded under the name of Spirifera trigonalis, the one is usually about 

 one inch and a half long, and two inches and a half wide ; tumid, and with a semicircular outline, the mesial 

 fold forming a square sinus in the margin, a deep hollow in the dorsal valve, but from being flattened on tlie 

 top, is scarcely raised above the surface of the ventral valve ; about twelve or fourteen strong, rounded ribs on 

 each side the mesial fold, and three on the mesial fold ; the centre one of which visually divides obscurely into 

 three, the others into two ; the cardinal area very broad, slightly curved. This is the shell figured and described 

 in the Mineral Conchology. The other comes nearer to the shell figured by Martin, it is much smaller, 

 rarely exceeding three-quarters of an inch in length, and one inch and a quarter in width ; only seven angular 

 ribs on each side the mesial fold ; the mesial elevation, instead of being flattened on the top, formmg a small, 

 square sinus in the margin, and being confounded with the surface of the ventral valve is acutely angular, 

 forms an exceedingly deep, triangular sinus in the margin, and rises very prominently from the ventral valve ; 

 the plaits on the mesial elevation of the first shell are of an equal size witli those on the sides ; but in tlie other 

 they are much smaller and more obscure. Both varieties are common in certain localities. 



