364 



THE CANADIAN NATURALIST. 



[Oct. 



from the convenient group of fucoids, into whicli palaeontologists 

 have thrown so many obscure and doubtful fossils. 



Mr. Billings describes the species as follows : 



" This species is found in the form of irregular, oblong-ovate or 

 depressed hemispherical masses, one end usually divided into two 



Fig. 3. Rusophycus Grerivillensis, var. b, half nat. size. 



parts by a furrow of more or less depth. The whole mass is gen- 

 erally crossed by numerous undulating wrinkles, which have a 

 transverse direction to that of the furrow. The more common 

 dimensions are from three to four inches in length, and from 



Fig. 3. Rusophycus carbonarius. 



two and a half to three and a half in breadth, but occasionally speci- 

 mens occur much larger and also smaller ; one of them is nine and 

 a half inches by five and a half, and, in addition to the principal 

 groove, exhibits two or three obscure furrows on each side." 



