BEEKMANTOWN AND CHAZY FORMATIONS OF CHAMPLAIN BASIN 519 



a r c u a t u m (— -- clintoni), O. allumettense, O. la- 

 marcki, Piloceras canadense) ; two of them ( O . 

 tnulticameratum, O. bilineatum) again are, to my 

 knowledge, known only from the Black river and Trenton stages of 

 the Canadian and Champlain basins, and are hence not strictly co- 

 existant in both basins in the Beekmantown and Chazy stages. 

 Orthoceras subarctiatum (= Spyroceras clin- 

 toni) and Protocycloceras lamarcki are among the 

 four common species cited by us before ; there are, hence, altogether, 

 six cephalopod species common to the Newfoundland and Canadian- 

 Champlain basins as against y6 species named in the two mentioned 

 lists, which are not common to the two embayments. To this must 

 be added a number of other forms described from Canada and not 

 known from Newfoundland and the 15 or more new nautiloid Beek- 

 mantown forms, from Canada and Newfoundland, described by 

 Hyatt, none of which appears to go out of its province. 



From these figures giving the number of identical species of ceph- 

 alopods of the Champlain and Newfoundland basins but one infer- 

 ence could be drawn, i. e., that during the Beekmantown and Chazy 

 periods the cephalopod faunas of the Newfoundland and the Cham- 

 plain-Canadian basins did not mingle to any noteworthy degree. 

 But we shall see later \see p. 525] that this inference based on com- 

 parison of beds that are not exactly equivalent, should not be given 

 great weight. 



Of the relations of the orthoceraconic and cyrtoceraconic Cham- 

 plain cephalopods to those of the corresponding western horizons, 

 we can get no more than a faint glimpse from the few forms which 

 are at present known from the Shakopee formation. One of these, 

 Endoceras ( ?) consuetum Sardeson is so closely related 

 to one of our Beekmantown types, that we could have ventured to 

 refer the latter tentatively to this western form. Another,- as yet un- 

 described, extremely closely septate cyrtoceracone from the Oneota 

 formation at Blanchardville Minn., is strikingly similar to Endo- 

 ceras montrealense Billings, possessing the same chamber 

 depth, position and relative size of siphuncle, though still differing 

 in a somewhat greater rate of growth and greater curvature. An 

 undescribed Cyrtocerina, which appears to be quite common in the 

 Shakopee formation at Dresbach Minn., is plainly a close relative to 

 the Point Levis form Cyrtocerina mercurius Billings, 

 with which it has the curvature and chamber depth in common. 

 We will now turn to the relations of the nautiloid genera. 



