84 NEW YORK STATE MUSEUM 



Machaeracanthus peracutus Newberry 

 1857 Machaeracanthus peracutus J. S. Newberry. Nat. Inst. Bui. p. 125 

 1862 Machaeracanthus peracutus J. S. Newber?-y. Am. Jour. Sci. [2] 



34: 74, text fig. 2 

 1873 Machaeracanthus peracutus J. S. Neivberry. O. Geol. Sur. Rep"t 



V. I, pt 2, p. 305, pi. 29, fig. 6 

 1889 Machaeracanthus peracutus /. S. Neivherry. U. S. Geol. Sur. Monogr. 



16: 40, pi. 29, fig. 6 and woodcut 

 Spines of moderate or large size, slightly curved, gradually tapering, 

 and traversed along the middle by a prominent ridge, which is distinctly 

 triangular in cross-section on one side of the spine throughout its entire 

 length, and more or less rounded on the other. Lateral edges sharp, apex 

 acute, external surface smooth or with extremely delicate striae which are 

 convergent inward at a slight angle with the external margins. 



Formation and locality. This species, which is the type of the genus, 

 has been previously supposed to be confined to the " Corniferous " (Colum- 

 bus and Delaware) limestone of Ohio. A few examples, however, have 

 been obtained within recent years from the Onondaga limestone of Leroy 

 and Lime Rock, in New York State. 



Machaeracanthus sulcatus Newberry 



Plate 3, fitjiire 6 



1843 " Ic h th y o d o r u 1 i t e " /. Hall. Nat. Hist. N. Y. pt 4, p. 174, woodcut 

 fig. 69 



1857 Machaeracanthus sulcatus J. S. Neivberry. Nat. Inst. Bui. p. 6 



1870 M a c h a i r a c a n t h u s sulcatus E. R. Lankester. Geol. Mag. 7 : 398, wood- 

 cut fig. 3 



1873 Machaeracanthus sulcatus J. S. Neivberry. O. Geol. Sur. Rep't, v. i, 

 pt 2, p. 305 



1886 Machaeracanthus sulcatus T. H. Lennox. Can. Inst. Proc. 3: 120 



1889 Machaeracanthus sulcatus J. S. Newberry. U. S. Geol. Sur. Monogr. 

 16: 40, pi. 29, fig. 5 



Spines of about the same size as the type, and differing from it princi- 

 pally in that the less strongly carinated face bears several prominent longi- 



