BEEKMANTOWN AND CHAZY FORMATIONS OF CHAM PLAIN BASIN 517 



group. Clarke records the species also from Illinois and the corre- 

 lation table referred to from the same formation in Tennessee. 

 These are all the species of Gonioceras hitherto known. The genus 

 was hence well established in the Mississippian sea and its trans- 

 gression areas in early Mohawkian time. The species here described 

 shows that the genus existed earlier, viz, in Middle Chazy time in 

 the Champlain basin. It is entirely missing in Europe and is hence 

 to be considered as a typical form of the American-Pacific basin. 



Crick has lately [1903] announced the occurrence of Gonioceras 

 in a series of Lower Silurian fossils from Kiachow in North China, 

 together with Actinoceras (Ormoceras) (iff. tenui- 

 f i 1 u m Hall and brachiopods of the same age. This exceedingly in- 

 teresting observation extends the habitat of the genus Gonioceras 

 across the entire Pacific- American basin and furnishes further evi- 

 dence of its having been characteristic of this very ancient oceanic 

 basin. 



As in the case of Xanno, which to our present knowledge is also 

 restricted to the American basin, the distribution of Gonioceras 

 would indicate either an immigration of these genera from the Chazy 

 basin into the Mississippian sea at the time of the beginning of the 

 Trenton transgression or, which is more probable, an earlier con- 

 nection of the two marine expanses and an origin of these forms in 

 a western region which as yet has furnished no fossils of early 

 Siluric age. 



Some very interesting facts are presented by the distribution of 

 the species of the genus Piloceras. This genus is so peculiar in its 

 characters that Hyatt erected a separate family for its reception, 

 and that it is not liable to be overlooked wherever occurring. There 

 have been described five species from the Beekmantown beds of the 

 Newfoundland embay ment. One species has been recorded from 

 the corresponding beds of Scotland and one is known from the Fort 

 Cassin beds. A small form has been described by Sardeson and 

 another modified type by Clarke, both from the Shakopee formation 

 of the west. The Shakopee is regarded by Winchell as probably 

 equivalent in part to the Beekmantown formation of eastern North 

 America. The present evidence points hence distinctly to the north- 

 western Atlantic as the center of distribution of this localized form, 

 whence it reached the British embayment of the Atlantic basin in 

 one species and on the other side entered the St. Lawrence chan- 

 nel and reached the Mississippian sea. 



A genus which may with propriety be cited here, though wo have 

 not found it in the Champlain basin, is Conoceras Bronn (Bathmo- 



