8o NEW YORK STATE MUSEUM 



Strata of the same horizon at Leroy, N. Y. One fairly well preserved 

 spine belonging to the New York State Museum is labeled as having been 

 derived from a "ravine 2^^ miles south of Truxton Corners, East branch," 

 the horizon being probably the same as the foregoing. Its characters 

 are somewhat indistinctly shown in plate 3, figure i. Typically the species 

 occurs in the Columbus and Delaware limestones of Ohio, but is appar- 

 ently also represented in the Hamilton of Milwaukee, Wis. 



Horizon. Ulsterian ; New York and Ohio. Erian ; Wisconsin. 



Genus phlyctaknacanthus Eastman 

 Arcuate spines of large size, with flat lateral surfaces, very broad at 

 the base, and gradually tapering to an acute point. Ornamentation and 

 other characters as in Acantholepis, except that the exserted portion is cer- 

 tainly unsegmented. Inserted portion triangularly expanded, thin walled 

 and hollow, recalling the conditions in the corresponding portion of 

 Stethacanthus. 



Phlyctaenacanthus telleri Eastman 



1898 Phlyctaenacanthus telleri C. H. Eastman. Am. Nat. 32: 551, text 



fig- 49 



1899 P li 1 y c t a e n a c a n t h u s telleri C. R. Eastman. Jour. Geol. 7 : 283 



The spines assigned to this species are scarcely distinguishable from 

 those of Acantholepis, their form, structure and ornamentation being prac- 

 tically identical. The exserted portion, however, has been definitely ascer- 

 tained to consist of but a single piece, and the inserted portion (unknown 

 in Acantholepis) appears to have been embedded in the soft parts in 

 similar fashion as in Stethacanthus. Admitting these remains to be fin 

 spines, it would certainly seem that a like interpretation should be applied 

 to Acantholepis. 



Genus apatkacanthus Woodward 



Fin spines elongated, slender, gradually tapering, extremely com- 

 pressed laterally ; sides ornamented with irregular series of fine tubercula- 

 tions ; posterior border with one (or two ?) close series of acute, hook- 

 shaped, downwardly pointed denticles. The genus is apparently closely 

 related to the preceding. 



