CARBONII^EROUS FOSSILS OF IRELAND. 109 



This is an exceedingly variable slicll, scarcely two specimens being found alike. I have taken as the type 

 of the species, however, those specimens which agree most nearly with Sowerby's original figure and descrip- 

 tion. In these there are usually about eight transverse, smooth, ridges, about a line in width, the rostral mar- 

 gin being prominent, and bearing a row of narrow, lengthened, tubercles, which give the ridges an elegantly 

 fringed appearance ; the dorsal valve is v6ry convex, and the beak large and tumid ; the ventral valve is but 

 slightly concave, it has flat, concentric ridges, and numerous spinulose puncta. The varieties difier in the irre- 

 gularity of the spines, and the concentric ridges becoming almost obsolete. Length one inch one line, width 

 one inch. 



PrODUCTA FLEXISTRIA. M'CojJ. (PI. XX. fig. 1 6). 



Sp. Ch . — Scmicylindrical, short ; front flattened ; beak globose, rather depressed ; mesial furrow slight, or 

 none ; surface coarsely striated longitudinally ; five or six large, smooth furrows on the sides, curved nearly three- 

 fourths of a circle, encircling a small, concave, smooth space. 



This shell is more nearly related to the Producta sulcata, than to any other of the genus ; it is, however, 

 more finely, and less rcgidarly striated, in addition to which the remarkably cvu'ved ribs on the sides distinguish 

 it from that, and every other species of the genus with which I am acquainted. The two valves are nearly si- 

 milar, the beak of the ventral one, however, being less globose than that of the dorsal, the front is square, and 

 the sides flattened, having, as before mentioned, a nearly circular, depressed, smooth space, near the extremity 

 of the hinge-line. Length one inch one line, width one inch two lines. 



Producta feagaria. Sow. sp. 



LeptKna i'ragaria. Sow. Geo!. Trans LeptEena fragaria. Phil. Pal. Fos. 



Sp. Ch. — Transversely oval, gibbous ; numerous large, spiniform tubercles, arranged nearly in quinciuix 

 order, alternately connected by concentric wrinkles ; no mesial furrow. 



This species is by many authors considered to be a variety of the P. rugata, but difiers constantly in being 

 nearly one-third wider in proportion to its length, being more convex, and in having the spines much more 

 numerous and more regularly placed ; the concentric rugEe are also smaller, more numerous, and more regular 

 than in that species. Length six lines, width eight lines ; frequently twice this size. 



Producta gigantea. Sow. 



Anomites giganteus. Martin, Pet. Derb — Productus giganteus. Sow. Min. Con. 



Sp. Ch. — Transversely oblong ; beak very gibbous; sides dilated into large, rounded ears; surface with 

 large, slightly flexuous ribs, covered by coarse, waving stria;, with small, irregular spines. Length two-thirds 

 the width. 



This very large species is remarkable for having longitudinal ribs, as thick as a man's little finger, on the 

 surface of the dorsal valve ; they are somewhat undulating, and accompanied by numerous, irregular, rough, 

 flexuous stria;. Width nine or ten inches. 



Producta granulosa. Phil. 



Producta granulosa. Phil. Geol. York. 

 Sp. Ch. — Transversely oval, gibbous; hinge-line very short; sides rounded, flattened; ventral valve slightly 

 concave ; surface with numerous, crowded, minute tubercles ; no mesial fiu-row. 



This little shell is almost destitute of ears, the flattened sides of the shell hardly deserving that name ; 

 the dorsal valve is very gibbous, particularly towards the beak ; the tubercles which crowd the surface have no 

 particular order of position ; they are very small and numerous ; there is no mesial furrow in either valve. 

 Length eight lines, width nine lines. 



2E 



