27 



Orthoceras pbkpaevum. (N. sp.) 



Description. — Length 3 or 4 inches ; diameter at the last septum about 

 3 lines ; section circular ; siphimcle very small and very nearly central ; 

 septa gently concave, about one line distant, the last three or four much 

 closer together. The chamber of habitation is 1 inch in length and tapers 

 slightly from the last septum towards the aperture which is |- a line nar- 

 rower than the diameter at last septum. Surface unknown but the cast 

 of the interior of the chamber of habitation shews a number of very obs- 

 cure annulations. Fragments of this species resemble Cyrtooeras exiguum 

 but the chamber of habitation is twice the depth and the shell does not 

 taper so rapidly. No perfect specimen has been seen but from the frag- 

 ments that have been collected I think this species must be 3 or 4 inches 

 in length, and is probably curved towards the smaller extremity. 



Locality and Formation. — PaUideau Islands. Northern part of Lake 

 Huron. Black River limestone. 



Collector. — ^A. Murray. 



HoLOPEA Pyubne. (N. sp.) 



Pig. 26. 



Description. — ObUquely turbinate ; spire depressed conical ; whorls 

 about three, ventricose, with a deeply impressed suture, crossed by deep 

 concave undulations which give to the shell a strongly varicose appear- 

 ance. 



The only specimen seen is imperfect consisting of only the apex and 

 2| whorls the base of the shell being imbedded in the rock. Width of 

 the part seen 9 lines ; width of the undulations about two lines. The 

 form is much like that of H. obliqua (Hall) but the deeply furrowed sur- 

 face shews that it is a very distinct species. 



The aspect of this species is very like that of the undulated forms of 

 Platyceras and in fact no difference between the genera Platyceras and 

 Holopea has ever been pointed out. 



Locality and Formation. — Paquette Rapids, on the River Ottawa. 

 Black River limestone. 



Collector. — Sir W. E. Logan. 



Holopea Nereis. (N. sp.) 



Description. — Shell turbinate ; spire conical ; apical angle from 75° to 80° ; 

 whorls about four, uniformly ventricose (in the cast of the interior) except 



