BEEKMANTOWN AND CHAZY FORMATIONS OF CHAMPLAIN BASIN 445 



Observations. The large size of the siphuncle marks this 

 species as one of the very primitive forms of the Cycloceratidae 

 for whose reception Hyatt has erected the genus Protocycloceras. 



From Spyroceras bilineatum this form is readily distin- 

 guished by its greater siphuncle and the absence of the longitudinal 

 surface sculpture. 



Protocycloceras (?) cf. furtivum, Billings (sp.) 



Plate 16, figure 3 



Orthoceras furtivum Billings. Geol. of Can. Pal. Foss. 1865. 

 1:348, fig. 337 



There occurs at the Spelman ledge, in Beekmantown formation D, 

 another type of annulated conchs, in which the annulations do not 

 pass straight transverse, but obliquely around the conch. It agrees 

 in this character and the somewhat wider intervals between the 

 annulations (7 in 20 mm, where the conch has a width of 8 mm), 

 with the above cited Beekmantown form, described by Billings, to 

 which we refer it here with doubt, owing to our failure to observe 

 either septa or siphuncle. In P. ( ? ) furtivum, the siphuncle 

 is described as tubular and in contact with the conch ; the septa 

 are unknown. The only specimen on which Billings based his de- 

 scription came from the Beekmantown beds, exposed in the rock 

 cutting of the Brockville & Ottawa Railway in the township of 

 Kitley. 



Family kionoceratidab 

 Genus spyroceras Hyatt 

 Spyroceras clintoni Miller (sp.) 



Plate 14, figure 4 ; plate 16, figure 5-7 

 Orthoceras s u bare u at urn Hall. Pal. N. Y. 1847. v. 1:34, pi. 



7, fig. 3 (lower part of drawing) 

 Orthoceras s 11 b a r c 11 a t 11 ra Billings. Can. Nat. & Geol. 1859. 



4:461 



Orthoceras clintoni Miller. Am. Pal. 1877. P- 2 ^4 



Hall was the first to describe the common annulated cephalopod 

 from the Chazy rocks here under consideration. Unfortunately his 

 type specimen which is at present in the American Museum of 

 Natural History is composed of fragments of two different species ; 

 for an inspection of the same after it had been taken out of its 

 plaster packing revealed the fact that the anterior part is a frag- 

 ment of a strongly annulated arcuate form while the posterior one 

 belongs to a smooth straight form. The two fragments do not fit 

 together properly. We have for this reason redrawn this composite 

 original specimen [pi. 14, fig. 4]. 



