Gkabau — Faunas of the Hamilton Group. 



315 



between the early and late Hamilton fauna is thus apparent. The introduc- 

 tion of the western species, Spirifer asper and StropJieodonta plicata, gives an 

 added interest to this bed. Its total thickness is not much over four inches, 

 the seventy-two species which it contains being crowded within that narrow 

 vertical range. Overlying it are several inches of almost barren shale, which 

 are followed by : 



x. The Stictopora bed. 



In this bed, which is often less than an inch in thickness, Stictopora 

 incisurata and Nacleospira concinna are extremely abundant, the rock often 

 being made up of the cemented fragments of the former, and shells of the 

 latter with crinoid joints. Weathering separates them from the rock, and they 

 may be picked up in great numbers and in a fine state of preservation. 



Stroplieodonta demissa lias almost disappeared, only two or three frag- 

 ments having been obtained from this bed. 



The following are its fossils : 

 Crustacea : 



1 Phacops ran a. c 



2 Cry pine us Boothi. r 



Pteropoda : 



13 Tentaculites bellulus. r 



Gasteropoda ; 



20 Platyceras Thetis, rc 



23 P. (Orthonychia) attemiatum. rc 



24 Platystoma (Diaphorostoma) lineata. c 



Lamellibranchiata : 



35 Aviculopecten exacutus. r 



40 Pterinea flabella. r 



41 Actinopteria decussata. rc 

 57 Palseoneilo muta. r 



G6 Cypricardinia indenta. c 



Brachiopoda : 



78 Craniella Hamiltonise. r 



79 Pholidops Hamiltonise. r 



82 Rhipidomella Vanuxemi (small), c 

 84 R. Penelope (small), r 



