CEPHALOPODA— HOLOCHOANITES. 

 Chazy of Lake Champlain region. Common. 



41 



III. Vaginoceras Hyatt. 



Differs from Cameroceras in having the siphonal funnels extend 

 beyond the preceding septum, even to the one before. Endo- 

 siphosheaths very numerous. Ordovicic. 

 4. V. oppletum Ruedemann. (Figs. 1236, 1237.) Ordovicic. 



Large (one meter or more), very slowly expanding; subcircular 



Fig. 1236, Vaginoceras oppletum, 

 section of fragment showing apical 

 end of endosiphocone, and the endosi- 

 phosheaths. (After Ruedemann. ) 



Fig. 1237. Vaginoce7'as oppleHim, en- 

 largement of part of siphuncular wall of Fig. 

 1236, showing structure and extent of septal 

 funnels, X 5' (After Ruedemann.) 



in section, with large living chamber, shallow camerae increasing 

 progressively (20 mm. in adult) ; older ones with organic deposits 

 often filling them ; sutures with ventral saddle ; siphuncle circular, 

 two fifths the diameter of the conch, subventran; surface smooth. 

 Common in the Lower Chazy (C) of Lake Champlain region, 

 of New York and Vermont. 



IV. Endoceras Hall (emended Hyatt). 



Like Cameroceras with siphonal funnels extending only to next 

 preceding septum, but without the lining of the siphuncle (endo- 

 sipholining) ; siphuncular cones (endosiphosheaths) fewer than in 

 Vaginoceras. 



