36 NEW YORK STATE MUSEUM 



Diagnosis. Shell small, length 12 mim; consisting of about five 

 volutions, the last one of which occupies three fifths of the entire 

 length of the shell; the four apical volutions are nearly straight, 

 but the body whorl is curved in such a way that the apertural 

 side appears straight, while the opposite .side formgi in outline a 

 regular arch, the hight of which, measured in the middle, is a 

 little greater than the width of the shell. Apical angle 38° ; 

 greatest width of valve between one third and one fourth of the 

 length. 



Aperture not observed. 



Ulrich has separated species in which the aperture exceeds 

 one half the whole hight of the shell, the shell arcuate and the 

 truncation of the lower extremity of the aperture not so apparent, 

 from Subulites and united them under the new generic designa- 

 tion, Cyrtospira. Our species' shows the first two generic char- 

 acters of this new genus in a marked degree, and stronger than 

 the type species, while the third, the character of the aperture, 

 is not observable. 



This species differs from other congeneric forms, notably from 

 C. p a r v u 1 a Billings from the Black river beds, C. a b b r e- 

 v i a t a Hall from the Trenton of New York, and the three 

 species described from the western Stones river and Trenton 

 beds, in its longer spire, more slender form and stronger curva- 

 ture. (Group 7) 



PTEROPODA 



hyolithus Eichwald (orthotheca Novak) 



Hyolithus rhine sp. nov. 

 PI. 2, fig. 12-15 

 Among the novel forms of the Rysedorph hill fauna is a speci- 

 men of Hyolithus, obtained from the reddish gray compact 

 limestone. 



Diagnosis. Form, an elongated triangular pyramid, tapering 

 at an angle of 16°; transverse section broadly triangular; ventral 

 face slightly convex; dorsal face roof shaped with subangular 

 crest; sides toward the aperture very slightly convex, toward 

 the apex, however, bearing a broad, shallow, longitudinal depres- 



