254 



Length of the best preserved specimen 2 inches ; diameter at the 

 larger extremity 9 lines, and at the smaller 4 lines ; diameter of the 

 siphuncle 1^ lines. The centre of the sipliuncle is about 1 line from 

 the centre of the septum. 



Another specimen, 5 inches in length, tapers from 14 lines to 3 ; and 

 has 9 septa in the 2 inches at the larger extremity, and 8 in 1 inch at 

 the smaller. 



In external characters this species closely resembles 0. deereseens 

 (Black River and Trenton), but differs in the form of the siphuncle, 

 ■which is cylindrical instead of moniliform. 



Locality and Formation. — L, Point Rich, M, Table Head, Neirfound- 

 land ; Quebec group. 



Collector. — J. Richardson. 



Orthoceras Allumettense (Billings). 



0. Allumettense (Billings.) Report G. S. C, 1857, p. 351. 



Remarks. — This species occurs at Table Head, in Divisions M and N ; 

 at Point Rich, in M ; and on the west side of Pistolet Bay, in N. In 

 Canada it occurs in the Chazy and Black River formations ; but has not 

 been found above the Black River limestone. The specimens from New- 

 foundland are all one-half larger than the largest that have been collected 

 in Canada. In other respects, I cannot make out any difference. 



Orthoceras HiESiTANS. (N. sp.) 



Variety of 0. Bigsbrji (Stokes) ; 0. tenuifilum (Hall.) 



Description. — Section apparently nearly circular, the transverse dia- 

 meter a little greater than the dorso-ventral ; siphuncle inflated between 

 the septa, a little less than one-half the whole diameter ; septa distant 

 about one-sixth the whole diameter. 



Only two specimens have been collected ; and both of these are curved 

 to a radius of about one foot. The siphuncle in one of these specimens 

 is in contact with the shell at the smaller extremity, where the diameter 

 is about one inch, and distant from it about one line, where the diameter is 

 nearly two inches. In the other it is two lines distant from the shell 

 throughout. 



Both specimens are somewhat distorted by pressure, and, therefore, 

 the dimensions cannot be given precisely. They are each about 5 inches 

 in length, 2 inches in diameter at the larger, and 15 lines at the smaller 

 extremity. 



