57^ NEW YORK STATE MUSEUM 



Plectoceras jason Billings (sp.) 



Page 484 

 See pi. 29 ; 30 ; 31 



1 Ventral view of a specimen showing the recurving costae and 



transverse lines 

 The original is from the lower Chazy beds at Valcoiir (B^ of sec- 

 tion) and now in the New York State Museum. 



Trocholites internestriatus Whitfield (sp.) 



Page 479 



2 Lateral view of a specimen which shows the surface sculpture 



of the first volution of the smooth shell of the earliest nepionic 

 stage, the transverse striation of the later nepionic stage and 

 the abrupt appearance of the ribbing with the neanic stage 

 \see text fig. 38] 

 The original is from the Beekmantown (Fort Cassin beds) of Fort 

 Cassin and now in the museum of Burlington University. 



Tarphyceras seelyi Whitfield (sp.) 



Page 465 

 See pi. 19, fig. i; pi. 20, fig. 5; pi. 21 



3 Specimen retaining part of the outer wall. A transverse section 



of this specimen is shown on plate 19, figure i 

 The original is from the Beekmantown (Fort Cassin beds A3) of 

 Valcour N. Y., and now in the New York State Museum. 



