638 PALEONTOLOGY OF ILLINOIS. 



SPHRAGIOPORA Ulrich. 



(For generic diagnosis, see page 398.) 



Although externally somewhat resembling the isolated colonies 

 of Botryllopora Nich., the species upon which this genus is 

 founded proves upon investigation very different. That genus 

 exhibits little to distinguish it from the FISTULIPORID^:, while S. 

 parasitica in no feature reminds us of that family. Taking only 

 the zooecial characters into consideration the genus agrees very 

 closely with both the FENESTELLHLE and ACANTHOCLADIIDJD. The 

 zoarium is however so very different that a reference to either 

 one of those families seems out of the question. 



SPHRAGIOPORA PARASITICA Ulrich. 



PL LXV, fig. 6, 6a. 



Zoarium a small disc-shaped body attached parasitically to 

 foreign objects; very frequently the strong supports of Lyro- 

 pora. Upper surface flat or a little concave; base smooth, form- 

 ing a margin around the raised celluliferous portion. Diameter 

 of zoarium, when mature, from 1 to 2 mm., height about 0.5 

 mm. The smallest specimen seen is 0.32 mm. in diameter. On 

 a mature example the zooecia apertures are arranged in an ir- 

 regularly radial manner about the center, upon the summits of 

 six to nine more or less elevated ridges. At first they form 

 only single rows, but at the outer margin the arrangement is 

 biserial. A cyclic arrangement is also more or less evident. 

 Apertures subcircular, about 0.09 mm. in diameter, generally 

 with a faint peristome, occasionally preserving rayed operculum- 

 like covers. A variable number of irregularly distributed acces- 

 sory pores and tubercles also present. 



Position and locality: Chester group, Chester, 111. What may 

 prove another species occurs attached to shells in the Upper 

 Coal Measures of Illinois. Its zoarium is comparatively higher. 

 and its zooecia apertures, so far as observed, not radially 

 arranged. 



