BRYOZOA. 447 



foundations of delicate setaB. Similar structures have been de- 

 tected in Bactropora simplex and in species of Rhombopora (e. g. 

 R. crassa.) The minute dark spots between the walls of the 

 zocecia in S. montifera and other species of the genus are prob- 

 ably of the same nature. 



The generic reference of the species is somewhat doubtful, and 

 there is little danger of confounding it with any species of 

 Stenopora known to me. The large acanthopores serve amply 

 in distinguishing specimens from Rhombopora crassa Ulrich, an 

 associated form. 



Position and locality: Coal Measures. The only examples 

 seen are from Casey ville, 111. 



ANISOTRYPA Ulrich, 1883. 



(Jour. Cin. Soc. Nat. Hist. Vol. VI, p. 275.) 

 (For generic diagnosis see page 376.) 



When I proposed this genus I supposed the hollow branches 

 and the large cell which occurs at sub-regular intervals among 

 the ordinary zocecia of A. symmetrica, were characters of gen- 

 eric importance. My acquaintance with Stenopora Lonsdale, 

 and Rhombopora Meek, at that time also was limited. Now, 

 since I have gone over the ground much more fully, I find that 

 both features are really of only specific importance. That I 

 failed to grasp the more significant characters is to be credited 

 to my ignorance of the close relationship existing between Ani- 

 sotrypa and Stenopora. This relation seems quite remote when 

 we compare only the typical species of the genera, but becomes 

 rapidly less distant with the extension of our comparisons, so 

 that now the only structures that are not common to the two 

 genera are the acanthopores. These are wanting in Anisotrypa 

 Another peculiarity that may hold good for the genus is the 

 ridge-like form of the interspaces separating the zocecia aper- 

 tures. The affinities with Rhombopora Meek, will be discussed 

 in my remarks upon that genus. 



Six species are known to me at this time, the oldest being 

 from the Keokuk group in Lincoln county, Kentucky, and is des- 

 cribed as Rhombopora elegantula in my "Am. Pal. Bry. v It 

 agrees in all essential respects with A. symmetrica, and like that 

 species, has occasional large cells. Two species, the A. fistulosa 



