362 Fossils of the Calciferous Sandrock. 



are more or less curved and have large sipkuncles, and several 

 are remarkable for the close approximation of their septa. 



ORTHOCERAS LAMARKI, (X. S.) 

 Fig. 11.-/, g, h. 



Description. — Annulated, tapering at the rate of about one line 

 to the inch, section circular, septa gently convex, eight in one 

 inch at a diameter of eight lines, more numerous towards the 

 apex, siphuncle cylindrical a little excentric, its diameter full one 

 third the diameter of the whole shell. The annulations are rather 

 prominent rounded ridges with regularly concave spaces between, 

 distant one line and a half from each other in a specimen eight 

 lines in diameter. 



The specimen figured is silicified, and it is impossible to say 

 whether the surface is striated or not. Three specimens have 

 been collected and all are a little curved. 



The septa increase rapidly in number towards the smaller 

 extremity of the shell and it would appear also that in some 

 individuals the distance is variable. In one specimen where the 

 diameter is five lines, there are five septa in half an inch, but in 

 the next half inch there are eight. 



The position of the siphuncle is also a little variable. 



Resembles externally the large curved 0. subarcuatum, (Hall) 

 of the Chazy limestone, but that species has more distant septa 

 and a siphuncle composed of large oval bead-like segments. 



Locality and formation. — Occurs at the Mingan Islands, and 

 also on Lot 12, Con. 12, Township of Godmanchester, Calciferous 

 Sandrock. 



Collectors. — Sir W. E. Logan, T. Richardson. 



ORTHOCERAS BECKI, (N. S.) 

 Fig. 11. — a. 



Description. — Section circular, smooth, slightly curved, taper- 

 ing at the rate of one line and one fourth to the inch ; septa 

 rather convex, nine to the inch at a diameter of seven lines ; 

 siphuncle cylindrical nearly marginal one third the whole diameter* 



This species is allied to one that occurs in rocks of the same 

 age in Scotland, figured in 3rd Edition of Siluria p. 217. 



Locality and formation. — Mingan Islands, Calciferous Sand- 

 rock. 



Collectors. — Sir W. E. Logan, J. Richardson. 



