390 REPORT ON THE STATE CABINET. 



GASTEROPODA. 



The following species have been identified with known forms, or deter- 

 mined as new : 



GENUS PLATYCERAS, Conrad. 

 Platyoeras niagarensis, Hall. 



jlcroculia niagarensis, Hall. Palaeontology, N. Y., II, p. 288, Plate 60, fig. 3. 



Formation and Locality. — In the limestones of Racine and Waukesha, 

 Wisconsin. 



GENUS PLATYOSTOMA, Conrad. 



Platyostoma niagarensis, Hall. 



Platyostmna niagarensis, Hall. Palseontology, N. Y., II, p. 287, Plate 60, fig. I. 



Formation and Locality. — In the limestones of Racine and Waukesha, 

 Wisconsin. 



GENUS STRAPAROLLUS, Montfort. 

 Strap AROLL us mopsus, n. s. 



PLATE XV, FIGS. 21, 22. 



Shell discoid; whorls four or more, cylindrical, very gradually enlarging, 

 the outer one sometimes a little flattened on the upper side for a 

 part of its extent ; suture line strongly marked ; umbilicus very 

 wide, and showing all the volutions. Spire depressed, rising little 

 above the surface of the outer volution. The proportion of height 

 and width is about as one to three. The individuals measure from 

 half an inch to seven-eighths of an inch in diameter. A specimen 

 having the latter measurement is three-tenths of an inch in height. 

 Some fragments of outer volutions indicate specimens of larger size. 



Specimens of this species, when compared with the figures of S. daphne, 

 Billings, have a very similar aspect on the lower side ; but the eleva- 

 tion of the spire, as given in the description, is much too great for our 

 species. 



Formation and Locality. — In limestone of the Niagara group, at Racine 

 and Waukesha, Wisconsin. 



