65 



of the Transition shales, in the upper part of which, 

 Hamilton species predominate, while the lower portion 

 contains mainly Marcellus species. 



ATHOL SPRINGS CLIFF. 

 Plate XXVI. 



This cliff extends from the dry ravine, which runs to the 

 lake-shore from Lake-side Cemeter\^ Station, to the Fresh- 

 Air-Mission Hospital at Athol Springs. In the ravine few 

 exposures are found, but some outcrops of the Trilobite and 

 Pleurodictvum beds occur. In the cliff, for some distance 

 above the ravine, the Strophalosia bed appears near the top 

 of the section; but the overlying beds are too much obscured 

 by talus and vegetation, to be visible. The whole of the 

 Transition shales appear below the Strophalosia bed. 



The Upper Marcellus Shales.— The Transition shales are 

 limited below by a hard layer, containing an enormous 

 number of pteropods, chiefly' of the two species Styliolina 

 £ssurella (Hall) and Tentaculites gracilistriatus Hall. The 

 two species appear very much alike on the rock, owing to 

 the fact that both exhibit the longitudinal "fissure" due to 

 compression. Tentaculites however, as noted before, is 

 readih' distinguished on close inspection, from Styliolina by 

 the raised annulations. Where the surface of the rock has 

 weathered, the pteropods appear in vast numbers, and in 

 great perfection. This laver appears for the first time on the 

 beach about the center of the section. It rises northward, 

 until near the Hospital it forms the top of the cliff, which 

 here has a height of from fifteen to twenty feet. At this 

 point the cliff projects into the water, and in climbing over 

 it, an opportunity is afforded for the examination of the 

 pteropod-bearing bed. This bed marks the top of the 

 Marcellus shales in this cliff. The shales below it contain 

 onh'^ characteristic Marcellus fossils. The predominating 

 species are: Tentaculites gracilistriatus Hall, Styliolina 

 fissurella (Hall), Lunulicardium fragile Hall, and Liorhyn- 



