BUFFALO SOCIETY OF NATURAL SCIENCES 165 



the incised lines. This specimen confirms the impres- 

 sion derived from E 1875, that the species is somewhat 

 more compressed than appears from Lindahl's figure of 

 the type specimen. 



Fig, 56. Cross-sections of Machmr acanthus major 

 A, section of distal third of spine; B, section at about middle. 



Machaeracanthus major Newberry 

 (PI. 53, figs. I, 2; text-fig. 56, A, B) 



This genus persisted in western New York beyond the Mid Devonic, 

 since it ranges into the Conodont bed (Genesee). It is represented 

 in the collection by a number of specimens. 



Specimens of Machaeracanthus are always found with one side 

 embedded in matrix, and as their knife-like lateral edges make it 

 impossible to extricate them without damage, no specimen has to our 

 knowledge ever been completely extricated from the matrix so as to 

 allow of study from both sides. Furthermore, few specimens show 

 the distal extremity in perfect preservation. One of our specimens, 

 E 1848 (PI. 53, fig. 2), consisting of the distal half of a large spine, 

 shows this portion to be of rather different conformation than is usual 

 in M. major, and it seems to us probable that the specimen represents 

 the under side of the spine, whereas other specimens that have been 

 figured represent the upper. This is of course only a supposition, 

 which cannot be established unless a complete spine of M. major were 

 extricated from the matrix, or one were sectioned at several levels, 

 which, however, would destroy the spine as a specimen. 



E 1847 Impression of an imperfect spine. Length, 140 mm.; 

 greatest width, 25. 



