226 Canadian Record of Science. 



was founded on a form referred to Monticulipora (Diplotrypa) 

 Whiteavesii, Nicholson. It is interesting to note that Mr. 

 TTlrich thinks that " this species (P. simulatrix var. orient- 

 alis, IJlrich) may really be the one referred to by Yanuxem 

 in 1842 (Geol. 3d Distr., N. Y., p. 46), when he speaks of 

 i: The puff-ball favosites {Favosites lycopodites) as being 

 highly characteristic and in great numbers in the Trenton 

 limestone of New York." Mr. Ulrich further states that 

 " the variety orientalis is common in the Trenton limestone 

 at Ottawa, Peterboro and other localities in Canada," and 

 in the figures on p. 248 he quotes from Canadian localities 

 a number of characteristic species which he there (loc. cit.) 

 figures as follows : 



21. Prasopora Selwyni, Nicholson (fig. 15a and b). This 

 species is restricted, in this volume, to a particular type, 

 such as was originally described by Nicholson from the 

 Trenton limestone of Peterboro, Ontario, Canada, and 

 Prof. IJlrich adds that " Foord says the species is abundant 

 throughout the Trenton formation at Ottawa, Canada. 

 Also that it has been found in the upper beds of the Chazy 

 at Nepean (Hog's Back, teste H. M. A.) near Ottawa. 



22. Prasopora oculata, Foord (figs. 15c and d). This in- 

 teresting form, which was originally described by Foord in 

 his "Contr. Micro-Pal. Cambro.-Silur. Eocks, Canada, p. 

 11," as coming from the Trenton formation at Ottawa and 

 Hull, Canada, has been recorded by Ulrich from several 

 localities in Minnesota. 



In connection with this species another Canadian Praso- 

 pora is referred to as being closely related, viz.: 



23. Prasopora affinis, Foord, also from the Trenton forma- 

 tion of Canada. 



Prasopora affinis, Foord, is here mentioned as being 

 closely related to P. Selwyni, Nicholson, the characteristic 

 difference separating P. oculata, P. affinis and P. Selwyni 

 being briefly and clearly outlined. All three species have 

 been discovered in the Trenton and Galena shales of Minne- 

 sota. 



