160 CATALOG OF FOSSIL FISHES IN THE MUSEUM 



merited with about 23 ridges, each composed of beads which are some- 

 what triangular in outline, with their apices directed downward, and 

 generally, each apex covered by the base of the triangle below. The 

 beading reduced or entirely absent from some ridges, particularly on 

 the posterior half of the spine, where the ridges are almost smooth, 

 and much finer than on the anterior part. Spaces between adjacent 

 ridges, in middle part of spine, greater than width of a ridge. Line 

 of demarcation between inserted and ornamented portions making an 

 angle of 45 degrees with front margin of spine. Inserted portion with 

 faint vertical striations and incisions. Posterior margin of each 

 lateral face with a row of a small denticles directed somewhat down- 

 ward. 



Remarks. — This ctenacanth spine seems to be the first recorded 

 from a Catskill horizon, if indeed the determination of the horizon in 

 the old record be correct. The spine differs from all others by the 

 pecuHarities of the ornamentation referred to above, and may be 

 recognized at a glance by the fact that the beading is absent entirely 

 from some of the ridges and also from other spots on the spine, so 

 that the smooth ridges and parts of ridges stand out clearly. 



We have found one specimen with which the present one may be 

 compared. This is the impression of the anterior half of a spine from 

 the Hamilton, i| miles northeast of Pomeroy, Onondaga County, 

 N. Y. (No. 874 Newb. Coll., Amer. Mus.) The specimen represents 

 a spine considerably larger than the type. None the less, its style of 

 ornamentation is so like that of the present species that we have no 

 hesitation in referring it to it. Ctenacanthus nodocostatus therefore 

 ranged from the Middle Devonic (Hamilton) to the top of the Devonic 

 (Catskill). This imperfect specimen, in the Newberry collection, 

 bears a label in Newberry's hand, reading Ctenacanthus compressus 

 Newberry. It is obvious, however, on comparison of the specimen 

 with the type of C. compressus and with another fine spine of the 

 latter species, both in the Newberry collection, that the present 

 spine is very different, and represents a distinct species. It appears 

 probable that Newberry did not make a squeeze of the impression, 

 but compared the impression directly, and this, superficially, re- 

 sembles the ornamented face of C. compressus. 



