(xrabatj — Faunas of the Hamlton (trout. 311 



Pteropoda : 



15 Styliolina fissurella. re 



Brachiopoda : 



82 Rhipidomella Vanuxemi. r 



88 Orthotlietes arctostriata. rc 



91 Stropheodonta perplana. r 

 100 Chonetes lepida. rc 

 105 Spirifer mucronatus. rc 

 119 Cyrtina Hamiltonensis. R 

 131 Liorhynchus multicostus. r 



The change thus, is in the disappearance of species, the three additional 

 forms observed (1, 119 and 131) probably occurring .in the shale beneath. 

 After this the shale becomes finer and less perfectly laminated, and the 

 fossils become rarer and rarer, until at four feet from the Encrinal limestone 

 (in the sections examined) it is practically barren, save for an extreme develop- 

 ment of Styliolina fissurella. Some thin layers seem to be filled with it, and 

 with Tentaculites gracilistriatus. Primitiopsis puuciulifera is also common. 

 Of the larger fossils, however, scarcely any trace is found. Extended search 

 £ave the following list : 



u. Fine, dark and poorly laminated shale. 

 Crustacea : 



6 Primitiopsis punctulifera. c 

 Pteropoda : 



14 Tentaculites gracilistriatus. C 



15 Styliolina fissurella. C 



Lamellibranchiata : 



51 Nuculites oblongatus. R 



Brachiopoda : 



79 Pholidops Hamiltoni*. R 



87 Orthotlietes arctostriata. R 

 100 Chonetes lepida. R 

 138 Tropidoleptus carinatus. R 



This change is probably a local one, affecting the region immediately 

 about Eighteen Mile creek and indicating a local change in currents and 

 sediment. 



