636 PALEONTOLOGY OF ILLINOIS. 



wide, and about one and a half times their diameter apart. On 

 the ridges chiefly, will be found small accessory pores, about 

 equal in number to the zooecia. 



Reverse face very finely striated, rather strongly rounded, 

 with numerous accessory pores arranged in a line near the 

 margins of the branches and pinnae. 



The shrubby appearance of the zoarium, the three ranges of 

 zooecia on the pinnae, and the accessory pores, induced me to 

 place this species with A canthocladia, the greater persistence of the 

 lateral rows of pores on the main stem of A. anceps being re- 

 garded as of only specific importance. I am not acquainted 

 with any bryozoan in American Carboniferous rocks that could 

 for a moment be confounded with A. fruticosa. What Swallow's 

 A. americana may be, has not been determined, but his meagre 

 description is nevertheless sufficient to show that it can not be 

 the same as the present species. 



Position and locality: Upper Coal Measures, near Springfield, 

 Illinois. 



DIPLOPORA Young and Young, 1875. 



(Proc. Nat. Hist. Soc. Glasgow.) 

 (For generic diagnosis see page 398.) 



The above name was proposed by the authors cited as a sub- 

 generic division of Glauconome (Pinnatopora). They include 

 under it only one species which they call G. (Diplopora) margi- 

 nalia, and describe as having a pore beneath each zooecia aper- 

 ture. As I have already shown, this supposed auboral pore is 

 the result of attrition whereby the convex front of the cell was 

 partially worn away, leaving the superior hemiseptum to sep- 

 arate the "pore" from the aperture. As, however, the species 

 is one of several deviating from Pinnatopora in wanting the 

 pinnae, I have concluded to adopt their name in a generic sense. 



Beside D. marginalia, which is from the Scotch Carboniferous 

 shales, I have met with three other species. One of these has 

 lately been described from England, by Mr. Vine, as Pinnato- 

 pora? simplex; the remainder are from Illinois, one from the 

 Lower Coal Measures, the other from the Chester. The latter 

 is somewhat doubtful as it differs from the others in having 

 its branches divided dichotomously. 



