﻿39 Descriptions of Species 13 



Distribution. — Especially abundant in the Canajoharie section. 

 It also occurs at Ft. Hunter and Tribes Hill. 

 The distribution of R. nuciditiformis is the 

 same as that of R. turgida, but it is more 

 abundant in the Tribes Hill-Ft. Hunter region. , 



Ribeiria, sp. (?) ,J) 



A fragmentary specimen of a Ribeiria which differs from both 

 R. turgida and R. nuciditiformis in the acuteness of the anterior 

 and from R. turgida in the flatness of the carapace, was found at 

 Canajoharie. 



Mollusca 



, CEPHALOPODA 

 Cyrtoceras gracilis, sp. nov. PI. 3, Fig. io. 



Cyrtoceras sp., Am. Pal., Vol. 3, Bull. 13, 1900, p. 19, pi. 17, figs. 5, 6. 



When this species was first described there was some doubt as 

 to whether it belonged to a new species or not. An examination 

 of more material leads to the conclusion that the species had 

 never been described. The specimens are all fragmentary but 

 show little variability. The description given in the above cited 

 paper is as follows : "A small specimen 12 mm. long and 8 mm. 

 in diameter with 5 septa to 3^ mm. can not be placed with any 

 described species." A more careful'description is now added: 

 Shell slender, arcuate. Transverse section oval. The tube ap- 

 pears to taper regularly. The septa are close together, 5 to 6 

 septa in 4 mm. being the average. The extent of the chamber 

 of habitation and the aperture were not observed. Septa 

 smooth and slightly concave. The siphuncle is small and close 

 to the ventral side (pi. 3, fig. 10). The septa are bent on one 

 side toward the chamber of habitation, as is well shown in the 

 figure (Bull. 13, pi. 17, fig. 5). 



C. acinacellum Whitfield (Bull. Am. Mus. Nat. His., Vol. 1, 

 p. 327, pi. 27, figs. 10-13) differs from it principally in the 

 siphuncle, which is situated near the outer margin. C. microco- 

 pium Dwight (Am. Jour. Sci., 3rd Ser. , Vol. 27, p. 256, fig. 11) 

 has the septa closer together. In C. dictys Billings (Pal. Fos. , 

 Vol. 1, p. 192, fig. 176) the septa are much farther apart. 



Distribution. — In the upper part of the Calciferous at Ft. 

 Hunter, Tribes Hill, and Canajoharie, N. Y. 



