BEEKMANTOWN AND CHAZY FORMATIONS OF CHAMPLAIN BASIN 449 



Billings himself distinguished in the above cited publication be- 

 tween the two species though I am not certain that the form which 

 he considers there as O . subarcuatum is indeed referable to 

 that species since Hall's drawings and descriptions would give, with- 

 out recourse to the original specimen, a wrong conception of the 

 species. 



Spyroceras bilineatum Hall (sp.) 

 Orthoceras bilineatum Hall. Pal. N. Y. 1847. 1 - 2 oo 



This species is cited here, because it has been repeatedly recorded 

 as occurring in the Beekmantown and Chazy rocks. Hall figured 

 a specimen referred to this Trenton species among the Chazy 

 forms [/. c. pi. 17, fig. 4, 4a], stating that it was given to him 

 by Dr Emmons as coming from the Calciferous sandstone of a 

 locality six miles east of Albany (Rysedorph hill), but was recog- 

 nized by him to be a Trenton form. 



Billings has also cited Orthoceras bilineatum as occur- 

 ring in the Chazy at Alingan (and also in the Black river limestone 

 and Hudson river group of Canada 1 ) and Whitfield 2 has described 

 and figured a Fort Cassin form as O . bilineatum Hall. The 

 latter is described here as a new species (Protocycloceras 

 whitfieldi). We have not found any annulated orthocera- 

 cones in either the Beekmantown or Chazy formation which could 

 be properly identified with the well known Trenton form S . bili- 

 neatum. 



Genus Orygoceras gen. now 

 Etymology: Oryx, an antelope ; ceras horn 



Orthoceracones with subcircular to depressed oval section ; in- 

 ternally annulated and externally smooth shell ; empty, tubular, 

 orthochoanitic siphuncle which is situated outside of center. 



Genotype : Orygoceras cornu - or y x Whitfield (sp.) 



Inability to refer Whitfiela s species Orthoceras cornu- 

 oryx from the Fort Cassin beds to any of the genera of ortho- 

 ceracones enunciated by Hyatt in his elaborate system of fossil Ceph- 

 alopoda, or even to any of the families which comprise the orthocera- 

 conic forms, as the Endoceratidae, Orthoceratidae and Cyclocera- 

 tidae has compelled us to propose a new genus for the reception of 

 this most peculiar form. 



The orthochoanitic character of the siphuncle will prohibit a ref- 

 erence to the first named family, the marginal position of the si- 

 phuncle and internal annulations dismiss the form from the Ortho- 



1 Can. Nat. & Geol. 1859. 4:462. 



2 Am. Mus. Nat. Hist. Bui. 1890. 3:35, pi. 2, fig. 5. 



