GltABAU- — ■f'AUWAS OF THE HAMILTON GROUT. 293 



Gasteropoda : 



30 Pleurotomaria capillaria. rc 



31 Loxonema Hamiltoniae. c 



32 L. delphicola (?). rc 



33 Belleroplion Leda. C 



Lameliibranchiata : 



50 Cypricardella bellistriata, R 



51 aSuculites oblongatus. rc 



52 Nuculites JSTyssa. rc 



55 Palfeoneilo temiistriata. R 



57 P. muta. R 



67 Modiella pygmsea. r 



68 Tellinopsis subemarginata. R 



69 Glyptocardia speciosa. R 



Brachiopoda : 



104 Strophalosia truncata. C 



105 Spirifer mucronatus c 

 109 S. granulosus. R 



116 (a) Araboccelia umbonata var.nana. r 

 129 Camarotoechia Dotis (?). R 



While this fauna has somewhat departed from the typical Marcellus 

 expression, its most important species are, nevertheless, Marcellus forms, or at 

 least such as occur in the Marcellus. The presence in this rock of a few 

 small specimens of Ambocoelia umbonata var. nana, is interesting, especially as 

 the specimens show a greater resemblance to Spirifer subumbona than do the 

 specimens in the Nautilus bed. 



With the disappearance of Strophalosia truncata, the Marcellus came 

 to a close in this region, and the true Hamilton epoch began, followed shortly 

 by the appearance of Nautilus magister and its associated forms. 



B. The fauna of the Lower Hamilton shales, or the Spirifer mu&ronatus 

 fauna. 



Throughout the Lower shales Spirifer mucronatus appears as the charac- 

 teristic fossil. It has usually its normal extended form, occasionally however 

 becoming extremely mucronate. It is a very abundant fossil, though in some 

 thin beds in the upper part of the shales and in some of the lowest beds it is 



