TRENTON CONGLOMERATE OP RYSE'DORPH HILL 13 



stictopora Hall 



Stictopora elegantula Hall. Pal. N. Y. 1847. 1:75 

 Small parts of a bryozoan were found, which, on account of 

 their fragmentary character, do not permit an accurate deter- 

 mination, but their oval apertures with strongly raised margins, 

 permit their comparison with Stictopora elegantula 

 Hall. (Group 5) 



CALLOPORA Hall 



Callopora multitabulata Ulrich 



M o n o t r y p e 1 1 a multitabulata Ulrich. Geol. and 

 nat. hist. sur. Minn. 14th an. rep't. 1886. p. 100. 



Many of the compact black limestone pebbles are fairly filled 

 with a branching, subcylindric bryozoan, the surface of which 

 could not be observed, as no weathered surfaces were found; 

 their sections, however, reveal their identity with Callopora 

 multitabulata Ulrich. Ulrich reports this organism from 

 the middle and upper Trenton of Minnesota, the Trenton of Ken- 

 tucky, Tennessee, and as probably occurring at Ottawa Can. 



(Group 5) 



prasopora Nicholson & Etheridge jr 



Prasopora simulatrix Ulrich, var. orientalis Ulrich. Geol. and nat. 

 hist. sur. Minn. 1895. v. 3, pt 1, p. 246 



In the black compact limestone pebbles of Rysedorph 

 hill, a few of the large hemispheric bodies, so widely 

 known from the Trenton under the designation Chaetetes 

 lycoperdon Hall, were found. As pointed out by Nicholson, 

 no definition of this species has ever been given by either Van- 

 uxem or Hall, or any subsequent writer, which can be regarded 

 as in any sense sufficient, while it is certain that this name 

 has been applied by different writers to wholly different forms. 

 As Vanuxem's figure, which gives the external form only, and 

 Hall's figures, which evidently include many forms, are no satis- 

 factory proof as to the species on which the name was founded, 

 Nicholson proposes to drop it altogether; Ulrich concurs, adding: 

 " It would not be difficult to show that since 1842 no less than 

 one hundred distinguishable forms have been included under 

 this indefinite general designation." 



