344 



about one-third the width from the suture. The margin outside of the 

 groove consists of an elevated rounded wire-like rim. The suture is 

 deeply impressed all the way to the apex. Surface with moderately fine 

 striae curving backwards from the suture to the margin. Under side 

 unknown, but evidently with a wide and deep umbilicus. 



Fig. 330. 



Fig. 331. 



Fig. 330. — Pleurotomaria Arabella. View of tlae spire. 



Fig. 331. — Ophihtal disjuncta. a, view of the spire; b, the lower side. 



Belongs to the same group with P. Canadensis, but is a smaller spe- 

 cies with more slender whorls, a narrower marginal band, and a deeper 

 suture. 



Locality and Formation. — Counties of Leeds and Grrenville ; Calciferous 

 formation. 



Collector. — -E. Billings. 



OpHILETA ? DISJUNCTA. (N. Sp.) 

 Fig. 331. 



Description. — Shell about one inch across, consisting of two or three 

 whorls which are usually a little separated from each other. Spire 

 deeply concave with an acute, strongly elevated carina following the 

 whorls to the apex, and situated about one-third the width from the outer 

 margin. Within the carina there is at first a shallow concave band, and 

 then a concave slope into the suture. Outside of the carina there is a 

 similar but barely perceptible concavity, below which the periphery is 

 uniformly convex. On the under side the whorls vary from uniformly 

 convex to very depressed convex, and sometimes flat along the median 

 line on approaching the aperture. The edge of the suture is usually at 

 first rounded and then angular. Surface with rather strong sub-squa- 

 mose strise. The whorls are sometimes separated two lines from each 

 other, but usually not so distant, and often almost in contact. The depth 



