78 
XAUTILOIDEA. 
apart. The surface of the cast shows that these numbered about 25 
in the whole circumference of the shell. jS^one of the finer orna- 
ments are preserved. 
Remarlcs. I think that a comparison of the figures and descrip- 
tion of the species enumerated above will be sufiicient to prove the 
identity of all of them with Billings’s species. The want of a figure 
of the latter to accompany the description probably led to its being 
overlooked by those who had not the opportunity of seeing the 
original specimen in the Museum of the Geological Survey of 
Canada. 
furthermore, Mr. Whiteaves observes that “ the eccentricity of 
the siphuncle in this species [as described by Billings], the only 
character by which it can be distinguished from Cijrtoceras Myrice 
of Hall and Whitfield, is more apparent than real, and is probably 
due to distortion or to the accidental and unequal erosion of the 
posterior end of the specimen.” 
Horizon. Silurian (Niagara Formation). 
Loeality. Offley Island, Kennedy Channel, Arctic America (lat. 
81° 16'). Represented by the type-specimen, transferred from the 
Museum of Practical Geology. 
ADDENDA i. 
CAMBRIAN SPECIES. 
Orthoceras Olorus, Hall. 
1847. Orthoceras rertehrale, Hall, Pal. of New York, vol. i. p. 201, 
pi. xliii. f. 5, a, h, c. (Changed to Olorus, Hall, in Miller’s Cat. of 
Amer. Pal. Foss. 1877, p. 245.) 
A very imperfect and eroded fragment has a label attached to it 
bearing this name in the handwriting of and initialed by J. W. 
Salter. It has a higher rate of tapering, and more acute and sep- 
arate ribs than any examples figured by Hall ; so that I think its 
identity with 0. Olorus is extremely doubtful. 
Horizon. Durness Limestone. 
Locality. Durness, Sutherlandshire. 
Represented in the Collection by a single specimen, presented by 
J. E. Lee, Esq., F.S.A., F.G.S. 
^ The following species were added to the Collection after the first part of 
the Catalogue was in type, and therefore they could not be inserted in their 
proper places. 
