PLATE XXXV 



PAGE 



Figs. 1-3. PLEUROTOMARIA ?? GREG ARIA Billings 290 



1, 2. Side view of an example enlarged and natural size. 

 3. Another view of the same. 



Ordovician (Canadian), Beekmantown Is., St. Ann, Canada. 



Figs. 4, 5. HORMOTOMA GRACILENS (Whitfleld) 293 



Two nearly complete specimens. Enlarged. 



Ordovician (Canadian), Beekmantown Is. (Division D), Beek- 

 mantown, New York. 



Fig. 6. DALMANELLA ELECTRA (Billings) 245 



Pedicle valve. X 2. 



Ordovician (Canadian), Kittatinny Is., Columbia, New Jersey. 



Figs. 7, 8. MACLURITES OCEANUS (Billings) 299 



Top and side views of the type. 



Ordovician, Quebec group, Port aux Choix, Newfoundland. 



Figs. 9, 10. ECCYLIOPTERUS DISJUNCTUS (Billings) 301 



9. View of the spire. 

 10. Lower side of the shell. 



Ordovician (Canadian), Beekmantown Is., Leeds and Gren- 

 ville counties, Canada. 



Fig. 11. TURRITOMA ACREA (Billings) 293 



Drawing of the type specimen natural size. 



Ordovician (Canadian), Division G of Quebec group, Port 

 aux Choix, Newfoundland. 



Fig. 12. ISOCHILINA SEELYI Whitfield 363 



View of a right valve with lateral and ventral edge views. X 4. 



Ordovician (Canadian), Beekmantown Is., Providence Island, 

 Lake Champlain, Vermont. 



Fig. 13. CYRTOCERINA MERCURIUS Billings 331 



Side view of the type specimen. 



Ordovician (Canadian), Point Levis, Quebec. 



Fig. 14. TROCHOLITES INTERNISTRIATUS Whitfleld 326 



Lateral view of specimen showing surface sculpture of the various 

 stages of the shell. 



Ordovician (Canadian), Beekmantown Is., Cassin beds, Fort 

 Cassin, Vermont. 



.Fig. 15. CAMEROCERAS and CYRTOCERINA 331 



A group of specimens showing occurrence and condition of preserva- 

 tion of these cephalopods in Maryland strata. The two left- 

 hand views represent a species of Cyrtocerina. The remaining 

 figures are of an undetermined species of Cameroceras. These 

 fossils occurred as imperfectly silicifled, iron-stained pseudo- 

 morphs on the weathered edges of rifts and caves in the lime- 

 stone. 



Ordovician (Canadian), Beekmantown Is., quarries at Legore, 

 Maryland. 



Figs. 1-3, 7-11, and 13 are after Billings; 4, 5, 12 are after 

 Whitfield; 6 after Weller; and 14 after Ruedemann. 



385 



