I06 NEW YORK STATE MUSEUM 



Winchell and Schuchert (1895, P- 3^1) have described as S ? 

 dodgei a form from the Trenton Hmestone (Glens Falls lime- 

 stone) at Sandy Hill, N. Y. This species, but little older than S . 

 albaniensis , differs in being broader, more acute posteriorly 

 and in possessing shorter and stouter spines. 



Our material has not furnished any evidence as to the interior 

 characters of the species. The foramen is large, situated relatively 

 far forward (4 mm from posterior margin) and connected by a 

 groove with the beak. 



6Tetranota bidorsata (Hall) 



This species, originally described and figured by Hall (1847, 

 p. 187) as Bucania bidorsata from the Lower Trenton 

 at Middleville and Watertown is not uncommon in the Snake Hill 

 shale at North Albany. The specimen figured has the lateral carinae 

 so well developed, and has such a wide volution, that it suggests 

 T. sexcarinata Ulrich, a western Stones River to Trenton 

 form; other specimens of the Snake Hill shale appear, however, as 

 good representatives of Hall's species. T. bidorsata is now 

 known (Bassler 1916, p. 1271) to range from the Stones River into 

 the Trenton and to occur from Nevada to New Jersey and Canada. 



7Kokenospira rara nov. 



In describing Kokenia costalis, the monotype of the 

 genus, Ulrich and Scofield (1897, p. 882) write: "We have seen 

 but a single imperfect specimen of this species, and were it not that 

 it belongs to a very interesting and easily recognized type, we would 

 scarcely be justified in describing it." 



The writer has to offer the same excuse of extreme biologic and 

 paleogeographic interest attaching to the imperfect specimen before 

 him, for it not only furnishes a new representative of the genus 

 Kokenospira Bassler (=Kokenia Ulrich and Scofield, which name 

 was preoccupied), but also suggests a northern paleogeographic con- 

 nection for the isolated Snake Hill shale fauna of New York. The 

 Snake Hill shale of the slate belt of eastern New York is of early 

 Trenton age ; so is the occurrence of K. costalis near Cannon 

 Falls (Minnesota) in the Prosser limestone, and the further import- 

 ant discovery of a Kokenospira at Frobisher Bay, Baffin Land, by 

 Schuchert (1900, p. 164). The genus is also represented in the Baltic 

 region (K. esthona Koken) and has thus a distinctly subarctic 

 distribution. 



