OKISKANY FAUNA OF BECK AFT MOUNTAIN 27 



of exposed whorls 2-3. Exterior of outer whorl with a low, revolving 

 lateral carina, which gives the upper surface a flattened aspect; other- 

 wise the surface is smooth. 



This species is distinguished from young forms of Autodetus 

 beecheri, in which the Spirorbis condition is completely inclosed 

 in the later growth of the shell, by the much less depth of its 

 whorls and the greater transverse diameter of the shell. 



Cornulites cingulatus Hall 



Plate 2, fl. 33-38 



1888. Cornulites cingulatus Hall, Paleontology of New York. v. 5, pt 2 

 (= 7, suppl.) p. 20, pi. 116, fig. 29 



The original of Corn, cingulatus is from the Helderbergian 

 (New Scotland beds) of New York, but its precise locality is not recorded. 

 It occurs occasionally in the Oriskany, where it presents a rapidly 

 expanding tube with coarsely and rather irregularly rugose surface, the 

 wrinkles being crossed by fine but sharp vertical striae. On the internal 

 cast the annulations have the aspect of insheathed cones and are not 

 unlike such casts of large Tentaculites, though of much less regu- 

 lar arrangement. 



Tentaculites elongatus Hall 



Plate 3, flg. 8-13 



1859. Tentaculites elongatus Hall, Paleontology of New York. 3 : 136, pi. 6, 



fig. 16-21 

 1892. Tentaculites cf. elongatus and Tentaculites sp. nov., Clarke, op. cit. p. 413 



The specimens of this species, described from the Helderbergian (New 

 Scotland) limestone of the Schoharie section, are not infrequent throughout 

 the Oriskany. Many of them show finely the sharp, filiform, concentric 

 striae which cover annulations and depressions alike. Approaching the 

 apex of the shells, the surface gradually loses its annulations but retains 

 the concentric striae ; for some distance the apical region is quite free 

 of any trace of annulations and where this part is found by itself 

 it presents the aspect of a quite distinct species. The internal cast of 

 the species was well characterized by Hall as resembling a series of 

 truncated obcones one above the other; thus these casts are altogether 

 unlike the exterior of the species. 



