347 



BELLEROPHON MACER. (N. sp.) 



Fig. 335. 



Description. Shell lenticular, with three or four slender whorls : dorsum 

 acute ; greatest width close to the umbilicus ; vertical diameter from nine 

 to twelve lines ; umbilicus large, exposing all the whorls, its width from 

 one-third to one-half the whole diameter ; the whorls enveloping apparently 

 to the depth of one-third. The edge of the umbilicus is narrowly rounded, 

 and from it to the dorsum the side of the outer whorl has a convex slope 

 becoming flat or even a little concave on approaching the periphery. The 

 width or thickness of the disc is about one-fourth of the diameter or a 

 little more. Surface unknown. 



This species is smaller and more compressed than B. Palinurus (ante, 

 p. 311,) and has a larger umbilicus, in which latter respect it differs, also, 

 from B. acutas (Sowerby). 



Locality and Formation. Counties of Leeds and Grenville ; Calcifer- 

 ous formation. 



Collector E. Billings. 



CEPHALOPODA. 

 ORTHOCERAS LAMARCKI (Billings.) 



ORTHOCERAS LAMARCKI (Billings). Can. Nat. and GeoL, vol. iv, p. 362, 



October, 1850. 



Fig. 336. 

 Fig. 336. Orthoceras Lamarcki. Side view ; a, section shewing the large siphuncle. 



Description. Annulated, tapering at the rate of from one line to one 

 and one-half lines to the inch ; section circular ; septa gently convex, 

 eight in one inch where the diameter is 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 well defined rounded 

 ridges, crossing the shell at right angles to the length, distant one line and 



