179 



Fig. 1, b, a portion of the poriferous surface enlarged. 



Fig. 1, c, another fragment, having elevated nodes upon the surface 

 of the branches. 



Fig. 1, d, an enlarged portion of the non-poriferous face. 



Fig. 1, e, a similar fragment of the non-poriferous face, partially cov» 

 ered by an incrusting coral which has the character of Chsetetes. 



This species occurs in the lower part of the Trenton limestone, near 

 Lowville, Lewis county. (State Collection.) 



iEGILOPS, (new genus.) 



Inequilateral, valves, somewhat trigonal, rounded on the base, slop- 

 ing abruptly from the beaks, which are incurved at the extremity. 



^GILOPS SUBCARINATA, 



Plate 4, fig. 1, a, b. 



Trigonal, with the beaks much elevated and incurved ; anterior slope 

 short, ending in a slightly rounded extremity, which continues into the 

 curve of the rounded base ; posterior slope long and straight ; surface 

 marked by a rounded ridge or carina extending from the beak nearly 

 to the base, and margined on each side by a corresponding depres- 

 sion. 



The form of this shell is peculiar and characteristic, the inequal- 

 ity of the valves is only apparent or due to pressure. It is clearly the 

 type of a genus which has not hitherto been noticed in the lower Siluri- 

 an rocks of this country, if in Europe. 



This species was found in the Trenton limestone, near, Lowville, 

 Lewis county. (State Collection.) 



MTJRCHISONIA SUBFUSIFORMIS. 

 Plate 4, fig. 2. 



Reference. — Paleontology of New- York, vol. 1, page 234, plate 39 

 %.2. 



The two figures of this fossil referred to, give but a very imperfect 

 idea of the species. Nearly all the specimens procured are so mutila- 

 ted that the true form is scarcely to be determined. The specimen 

 now figured is the most perfect one that has fallen under my observa- 

 tion, and will serve to give a better idea of the form and proportions of 

 the species, than those heretofore given. It preserves five volutions, 

 two volutions of the apex are broken off The specimen is scarcely at 



