36 GEOLOGICAL AND NATURAL HISTORY SURVEY OF CANADA. 



ByTHOPORA ? DELICATULA, McholsOn. 



Chaetetes delicatula, Nicholson, 1875, Pal. Ohio, vol. 2, p. 199, pi. 21, figs. 9-9a. 

 VVhiteaves, 1880, Geol. Sur. Can., Rep. Progr.,' 1878-79. 



A single specimen of this species is attached to a slab collected at 

 Stony Mountain in 18*75, by Dr. E. W. Ells. The species is a common 

 one in the upper beds of the Hudson River or Cincinnati group in Ohio 

 and Indiana. 



ByTHOPORA STRIATA. (N. Sp.) 



(Not figured.) 



This name is proposed for a species represented in the Manitoba col- 

 lections and sometimes found associated with B. delicatula, Nicholson, 

 at Middletown and other localities in Ohio, where the upper beds of the 

 Hudson River group are exposed. The branches of its lamose zoarium 

 are usually more slender than those of that species, being rarely more 

 than one millimetre in diameter. They also bifurcate at shorter inter- 

 vals, the length of the latter varying between two and four mm. The 

 apertures of the zocpcia too, are more oblique and drawn out ante- 

 riorly, and are arranged between somewhat irregular rounded longitu- 

 dinal ridges, with fiive or six in a space two mm. long. Ten to fourteen, 

 of the ridges suffice to encircle a branch. These ridges are strongest 

 near the base ot the zoarium, graduall}^ fading away toward the grow- 

 ing extremities of the stems. 



In B.fruticosa, Miller and Dyer, B. arctipora, Nicholson (species) B. 

 delicatula, Nicholson, and other species known to me, an arrangement of 

 the apertures of the zooecia in diagonally intersecting series prevails, 

 while in B. striata, near its base at any rate, the longitudinal arrange- 

 ment is the most conspicuous. 



The Manitoba specimen was collected by Dr. R. W. Ells at Stony 

 Mountain in 18V5. 



MONOTRYPELLA QUADRATA, RomingCr. 



Chsetetes quadrata, Rominger, 1866, Proc, Phila., Acad. Nat. Sci., p. 116- 



" rhombicus, Nicholson, 1874, Quart. Journ. Geol. Soc, vol. 30, p. 507, pi. 



29, figs. 11-116. 

 "■ " " 1875, Pal. Ohio, vol. 2, p. 201, pi. 21, figs. 12-1 2a. 



" " «* 1876, Ann. and Mag. Nat. Hist., Ser. 4, vol. 18, p. 



86, pi. 5, figs. llh. 



