90 



PALEONTOLOGY OF NEW-YORK. 



481. 1. CYCLONEMA CANCELLATA. 



Pl. XXVIII. Fig. i a-s- 

 Littorina canceMata. Hall, Geol. Rep. 4lh Dist. N. York, 1843, pag. 72 tmd 73, figs. 5 and 6. 



Obliquely sub-conical or globose, with a short spire ; volutions about four, rounded, rapidly 

 increasing from the apex so that the last one occupies almost the whole bulk of the shell ; 

 aperture scarcely expanded ; surface marked by prominent threadlike lines, coincident with 

 the spire, which are decussated by finer elevated strise in a slightly oblique direction. 



The size of this shell varies from the most minute form, as in 1 a, to the largest figure 

 represented. In young shells the decussating striae are usually well preserved, while they 

 gradually become obsolete in older specimens, which are likewise frequently distorted by 

 pressure. 



Fig. 1 a, b, c, d. Views of several specimens, showing an increasing size and slight variation 



in form. 

 Fig. I e. View of the aperture, the shell being slightly compressed in a vertical direction. 

 Fig. If, g. View of the front of the shell, and aperture of the same. 



Positio7i and localities. This species is quite abundant in the lower green shale at Sodus, 

 Wayne county, and occurs in other localities between that place and Rochester, where it is 

 found in the upper green shale. {State Collection.) 



482. 2. CYCLONEMA VENTRICOSA {n. sp.). 



Pl. XXVIII. Fig. 2 a, b, c. 



Shell ventricose, sub-conical ; volutions about three, rapidly enlarging from the apex ; mouth 

 of the size of the last volution ; surface marked by strong elevated sub-imbricating striee 

 parallel to the direction of the volutions. 



This shell resembles the last, but it is more elongated and the strige parallel to the volutions 

 are very sharp and distinct, with obsolete decussating striae. The shell is also larger than is 

 usual for the preceding species, and has one volution less. 



Fig. 2 a. Front view of the shell. 



Fig. 2 b. View of the mouth. 



Fig. 2 c. A portion of the surface enlarged, showing the character of the striae. 



Position and locality. In the lower green shale, Sodus, Wayne coimty. 

 483. 3. CYCLONEMA? OBSOLETA {n. sp.). 



Pl. XXVIII. Fig. 3 a, b. 



Sub-globose or ovoid ; volutions scarcely three, the last one occupying almost the entire 

 bulk of the shell ; spire scarcely elevated, consisting of less than two minute whorls ; mouth 

 oval oblong ; surface finely striated transversely to the direction of the volutions. 



