GUELPH FAUNA IN THE STATE OF NEW YORK 37 



constellata Hall of the Coralline (Cobleskill) limestone, but the latter 

 has the astrorhizae on monticules, a feature not shown in the Rochester 

 specimens. 



Sir William Dawson, in Life's Dawn on the Earth, p. 160, describes 

 and figures a form from the Guelph which shows such astrorhizae without 

 monticules, and the same closely laminated interior. Sections obtained 

 from the Rochester specimens show that the mass is first divided into 

 " latilaminae," then again in closely arranged laminae, through which pillars 

 pass continuously. On the basis of these structures the specimen is con- 

 sidered a true Stromatopora, and as showing no noticeable differences from 

 Dawson's Coenostroma galtense. The latter was regarded by 

 Nicholson as probably identical with Str. typica Rosen. This author 

 also states that Coenostroma constellata (Hall) Spencer 1 , from 

 the upper Niagaran of Hamilton Ont., does not appear distinguishable 

 from C. galtense Daws. 



This species forms numerous large concentric masses in the upper 

 Guelph of Oak Orchard creek. A good specimen exhibiting the astror- 

 hizae in fine preservation was also obtained from the dark crystalline lime- 

 stone directly underlying this layer and associated with Enterolasma 

 c al i c u 1 u s in abundance. In the lower bed occur very frequently cavities 

 of large size, which are either entirely vacant or filled with a more or less 

 loose mass of small, white, dolomite crystals. The shape of these cavities 

 and the occasional retention of one or two concentric layers indicate that 

 they originated from the dissolution of masses of Stromatopora. 



01.ATHRODICTYUM: Nicholson & Murie. 1878 

 Clathrodictyum ostiolatum Nicholson 



Plate 1, fig. 10-12 



Stromatopora ostiolata Nicholson, An. and Mag. Nat. Hist. 1873. ser. 4. 



12:90, pi. s, fig. 1, a 

 Stromatopora ostiolata Nicholson, Paleontology Prov. of Ontario. 1874. 



pi. 1, fig. 1, ia; 1875, p. 63 



1 Univ. State of Missouri. Bui. 1. 1884. p. 48. 



