CARBONIFEROUS FOSSILS OF IRELAND. 



139 



Martinia. M' Coy. 



Gen. Ch. — Hintrc-linc shorter than the width of the slicll; dorsal edges of the cardinal area obtusely 

 rounded ; surface smooth ; spiral appendages small. 



The short-hino-ed, smooth Spirifers, were distinguished long ago bythat excellent artist and friend of Mineral 

 Concholocfy, Mr. William Martin, and placed by him in a separate division from the long-hinged, ribbed species ; 

 they wore afterwards confounded together by the late Mr. Sowerby, under the general name of Spirifer, in the 

 Mineral Conchology ; they were then separated again by Professor Phillips, in his admirable Geology of York- 

 shire, and form the fourth division of his genus Spirifera ; and more recently Von Buch, in his memoir on the 

 Fj,, 22. genus Delthi/ris, forms of them his second division of the Spiriferce, but 



hitherto no author has named, or fully characterized, this most natui-al genus. 

 The spiral appendages, instead of filling nearly the whole shell, as in the true 

 Spirifers, are so small as only to occupy the upper or rostral half of it (fig. 

 22j. Thus furnished with internal as well as external characters, I have no 

 hesitation in keeping those as a distinct genus of the great family of Spirifers, 

 and dedicating it to the author of the Petrificata Derbiensia, to whom we owe 

 the first figures and descriptions of the more abundant species. Nearly all 

 the species of this genus, and some of Athyris, are united by foreign Palysontologists under the name Spirifer 

 loBvigatus. I would not have noticed this were it not that some recent British writers have done the same. I 

 agree perfectly with Professor Phillips, who has described most of them, in thinking them distinct. 



Martinia decora. Phil sp. 



Spirifera decora. Phil. Geol. York. 



Sp. Ch. — Orbiculai-, convex, smooth; beak of the dorsal valve prominent; cardinal area short, triancrular ; 

 mesial ridge obscure, divided by a longitudinal sulcus. 



This is a rare species, approaching very closely in its character to some varieties of the M. symmetricu. 

 Length one inch six lines, width one inch five lines. 



Martinia elliptica. Phil. sp. 



Spirifera elliptica. Phil. Geol. York. 



Sp. Ch. — Transversely elliptical; mesial fold wide, flattened, scarcely perceptible, except at the margin; 

 surface with very fine radiating strise, decussated near the beak by fine, concentric wrinkles ; width nearly 

 double the length. 



This is a very pretty shell, but not common any where; the radiating striaj, though constant, are scarcely 

 perceptible ; the concentric markings vanish towards the margin, and become nearly obsolete in old shells. 

 The beak and cardinal area rather large. Length one incli five lines, width two inches three lines. 



Martinia glabra. Mart. sp. 



Anomites glaber. Martin, Pet. Derb — Spirifer glaber. Sow. Miii. Con Spirifera glabra. Phil. Geol. York (pars). 



Sp. Ch. — Transversely oval; much wider than long, depressed, sharp edged; mesial fold very wide and 

 prominent ; cardinal area variable ; surface smooth. 



This species is liable to much variation in the proportion of length to breadth ; the deptli and cardinal 

 area also vary occasionally, but it is never so rounded in outline, so deep, or with so large a cardinal area, as 



however, inclined a distinguished writer to include them all in one genus, and a recent author has gone so far as to con- 

 sider them all as varieties of one species. 



