40 GEOLOGICAL AND NATURAL HISTORY SURVEY OP CANADA. 



DiCRANOPORA FRAGILIS, BillillgS. 



Ptilodictya fragilis, Billings. 1886. Catal. Sil. Fos. Antic, p. 9. 

 Stictopora fragilis, Whitfield. 1882. Geol. Surv. Wise, vol. 4, p. 253, pi. 11, 

 fig. 24. 



This species, though Dever common, is to be found at many localities 

 where the upper beds of the Hudson Elver or Cincinnati group (or 

 their equivalents) are exposed. Several segments, more or less com- 

 plete, were noticed on the slabs from Stony Mountain. The species 

 may be recognized by the oblique direction of the two or three marginal 

 rows of cells. The segments vary from six to ten mm. in length and 

 15 to 2-0 mm. in width, and have the upper or broadest extremity 

 divided dichotomously. The branchlets are short and, when in a good 

 state of preservation, have their extremities slightly thickened and 

 solidified for articulation with the succeeding segment. The lower 

 end of each segment is often obtusely pointed. There are eight to 

 twelve rows of zooecia on each face, of which the four or five central 

 ones are arranged between low longitudinal ridges. On old examples, 

 these ridges are finely granulose. 



Collected by Mr. T. C. Weston in 1884. 



DiCRANOPORA EMACERATA, Nicholson. 



Ptilodictya emacerata, Nicholson, 1875, Ann and Mag. Nat. Hist, sec. 4, vol. 15 



p. 179, pi. 14, fig. 3-36. 

 " " " " Pal., Ohio, vol. 2, p. 261, pi. 25, fig. 5-56. 



This species, represented in the Manitoba collection by a single im- 

 perfect segment, differs from D. fragilis in its smaller size, there being 

 only from four to six rows of cells. The usual number is five, with one 

 on each side oblique and the central rows longitudinal. The segments 

 are also only about four mm. long and one millimetre or less wide. 

 In other respects the species agree very closely. 



The specimen is attached to a slab collected in 1884 by Mr. T. C. 

 Weston at Stony Mountain. 



G-ONiOTRYPA, n. gen. (provisional). 



Zoarium jointed ; segments small, bifoliate, each face with a strongly 

 elevated central ridge, imparting a lozenge-shape to the segments in 

 •cross-sections. Zooecia ranged in longitudinal rows on each side of 

 the median ridge, their apertures oval, and directed more or less 

 obliquely outward. 



