105 



Zaphrentis Canadensis. CN. sp.) 



Petraia Cahadbnsis. — Report on the Geology of Canada, now in the preag, 



p. 208, fig. 205. 



Fig. 93. 



Fig. 93. — Zaphrentis Canadensis. — a, side view ; 6, longitudinal section, shewing 

 the form of the cup and internal structure ; c, transverse section 

 of one half of a specimen just above the bottom of the cup. 



Description. — Corallum turbinate, more or less curved, often nearly 

 straight, expanding to a width of from 1 inch to li inches in a height of 

 3 or 4 inches. Cup from | to 1 inch in depth, the bottom flat or irregu- 

 larly convex, and its width (at the bottom) equal to three-quarters of the 

 whole diameter. Radiating septa at the margin of the cup in a specimen Si 

 inches in length and | inch in diameter, about 150, alternating in size. 

 In the same specimen, the radiating septa close to the bottom of the cup 

 extend inwards 2 lines from the outer wall, the latter being 1 line in 

 thickness. In a longitudinal polished section, all the central portion is 

 seen to be filled by transverse diaphragms, three or four in two lines. 

 Surface with a few obscure undulations of growth, and, when worn, with 

 distinct septal striae. 



The specimens are numerous, and vary in their length, diameter, and 

 amount of curvature ; some are strongly curved in the lower, and straight 

 in the upper half. The septal fossette has not been observed, and it is 



