FOSSILS OF THE NIAGARA GROUP. 397 



the margins of which are prominent ; the upper part of the volu- 

 tions are marked by fine transverse strise, which are directed gently 

 backwards from the suture to the revolving band. 



This species very closely resembles specimens of the M. logani of the 

 Guelph limestone of Canada West, but the volutions of that species are 

 more ventricose, and the spire more rapidly ascending. 



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

 at Racine, Wisconsin. 



MuRcmsoNiA hercyna'? Billings. 



Compare Pleurotomaria gonopUura, W. & M. ; in Mem. Bost. Soc. Nat. Hist., I, p. 98. 1865. 



In a paper by Mr. Billings, already cited, he has described Murclii- 

 sonia hercyna, a conical shell with flattened volutions and without a 

 carina. Among the Wisconsin collections from Racine there is a single 

 specimen of similar form, preserving about four or five volutions which are 

 of precisely similar character, except that they are a little more rapidly 

 expanding, and the two lower ones show a slight convexity of the upper 

 part of the volution. The cast of the interior has the volutions sub- 

 angular above and below. 



GENUS EUNEMA, Salter. 



EUNEMA 1 TRILINEATA, HaLL. 

 PLATE XV, FIG. 3. 



Shell turreted ; spire ascending, composed of four or five volutions, which 

 are moderately rounded and gradually increasing in size to the last 

 which is somewhat ventricose. Surface of volutions marked by 

 slender revolving lines or ridges, crossed by close concentric striae 

 which in some places are elevated in bands or fascicles. 



The surface characters are remarkable for a shell in this geological 

 position, and more nearly resemble those of the Devonian or Carbo- 

 niferous fauna. 



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

 at Racine, Wisconsin. 



