350 



ORTHOCERAS ORDINATUM. (N. sp.) 



Description. This species tapers about one line and a-half to the inch ; 

 section apparently circular ; siphuncle cylindrical, about one line in diame- 

 ter where the diameter of the shell is five lines, its centre distant one and 

 a-nalf lines from the margin. There are twelve moderately concave septa 

 to the inch. Surface apparently not annulated. 



The specimens are very imperfect, but they show that this is an ordinary 

 form, probably when full grown eight or ten inches in length. It is not 

 quite certain whether the section is circular or ovate. At all events it 

 must be very nearly circular. 



Locality and Formation. St. Ann's and Township of Oxford ; Calci- 

 ferous formation. 



Collector. E. Billings. 



ORTHOCERAS VETERATOR. (N. sp.) 



Description. A fragment of this species has a dorso-ventral diameter 

 of nine lines, and a lateral diameter of eleven lines. Septa deeply con- 

 cave, eight in three lines. Siphuncle cylindrical, three lines in thickness, 

 in contact with the shell. Another specimen is eight lines in diameter ; 

 siphuncle three lines ; septa nine in three lines. 



This species has the septa much more concave than they are in the 

 figure of 0. primigenium given by Prof. Hall. Both of the specimens 

 are distorted, and the section may be oval. 



Locality and Formation. Township of Oxford ; Calciferous formation. 



Collector. E. Billings. 



ORTHOCERAS GLAUCUS. (N. sp.) 



Description. Small, slender, very gradually tapering ; section ap- 

 parently circular. The siphuncle is cylindrical, three lines in diameter, 

 and in contact with the shell. There are seventeen deeply concave septa 

 to the inch in one specimen, and fifteen in another. The proportional 

 diameter of the siphuncle to that of the shell cannot be made out with 

 certainty, but it appears to be one-third of the whole section. The shell 

 is not annulated. 



This species has a larger siphuncle than has 0. deparcum. It resembles 

 0. repens (ante, p. 312), but has a larger siphuncle. 



Locality and Formation. Township of Oxford ; Calciferous formation. 



Collector. E. Billings. 



