Silurian Fossils of Canada* 



171 



ciated with the genera Opliihta and Maclurea in this country. 

 Their Maclurea PeacJiii has a long spiral operculum, very unlike 

 anything then known on this side of the Atlantic, and it was not 

 suspected that the genus Plloceras would ever be found here at all. 

 But we have now not only a species of Piloceras (from the Cal- 

 ciferous Sandrock) but also Maclurea Atlantica (from the 

 Chazy) which latter species has an operculum almost identical 

 with that of 0. PeachiL When it is considered that evidence of 

 this kind as it accumulates increases in its demonstrative power in 

 a much higher ratio than do the mere number of the species (or 

 the facts which constitute the data) the correctness of the view 

 that the Scottish and Canadian rocks above referred to are of the 

 same age, cannot fail to be perceived. 



Piloceras Canadense. N. s. 



Fig. 16. 



Fig. 16. — Side view of the solid portion of the siphuncle shewing distance 

 of tlie septa. 



Description. — Of this species we have, besides several detached 

 siphuncles, two fragments, each exhibiting some of the septa. The 

 form, as nearly as it can be determined is that of a short thick 

 curved Orthoceratite. The length of the largest specimen 

 appears to have been about ten inches, and the diameter at the 

 aperture four or five inches. The transverse section is oval, the 

 narrowest side being that of the concave curvature. The siphun- 

 cle of one specimen is, at two inches and three-fourths from the 

 apex, seventeen Hues in diameter in the dorso-ventral direction, 

 and fourteen lines in the transverse direction. On the surface of 

 this specimen there are, on an average, six septal rings in the 

 length of one inch. Judging from the appearance of another spe- 



