344 EIGHTEENTH REPOKT ON THE STATE CABINET. 



The species differs from the P. lalteata of Phillips in the more 

 angular form of the volutions, and the band distinctly marking the carina. 

 This feature of the volution gives a different form of aperture ; while the 

 New- York species has a strong thickened columella, which is not shown in 

 figures of the European species. 



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

 Wisconsin. 



PLEUROTOMARIA HALEI. 



Pleurotomaria halei : Ann. Rep. of Progress, Geol, Sur, of "Wisconsin, 1861, p. 34. 



An examination of some specimens of this species in the collection show 

 that the spiral band was expanded and extended into a prominent sharp 

 carina or alation, having a width, on the last volution, of an eighth of an 

 inch, and marked by strong transverse striae. 



This species has been found only at Racine, in Wisconsin. 



PLEUROTOMARIA AXION (n. s.). 



Shell subconical, volutions about four, the apicial one minute, the first 

 three volutions small, rounded and gradually expanding, while the last 

 one becomes extremely ventricose and evenly rounded : suture line 

 deeply impressed and more than half of the preceding volution exposed 

 above it. The aperture has been subcircular and very large. 



Surface marked by strong revolving striae, which are crossed by concen- 

 tric striae of less strength, giving a cancellated structure. The middle of 

 the volution is marked by a rather wide and little elevated band, upon 

 which the striae have a slight retral curve. 

 The surface characters are very similar to those of P. lucina of the 



liOwer Helderberg and Hamilton groups of New- York ; but the shell is more 



elevated and attenuate towards the apex, and the suture is more deeply 



marked. Its form is intermediate between the species just cited and 



P. lineata.* 



The species described is from a gutta percha cast from an impression in 



limestone. 



Formation and locality. In limestone of the age of the Niagara group, 



at Bridgeport, Illinois. 



I 

 GENUS MURCHISONIA (Phillips) 



MURCHISONIA CONRADI (n. s.). 



Shell turreted, somewhat rapidly ascending, consisting of about seven 

 volutions which are distinctly carinated on the middle or scarcely above 

 the middle. Above the carina the surface is slightly concave, and below 



*See Fifteenth Report on the State Cabinet, plate 5, page 165. 

 40 



