PROUT — NEW SPECIES OP BRYOZOA. 411 



respondence with the dissepiments, being to the number of 

 14-15 in each of the two lines in the length of the rays. 



Dissepiments depressed, short, round, thickened at junc- 

 tion with longitudinal rays. 



Feaestrules mostly quadrangular, but occasionally sub- 

 oval from thickening of the dissepiments at their junction. 



Veils or chalices small, tapering upwards, placed in a line 

 above the insertion of dissepiments and about midway be- 

 tween the obverse and reverse. In worn specimens the chal- 

 ices become distinct, showing three to each fenestrule, while 

 the tubercles disappear entirely. 



Reverse, striated where worn. 



Geol. jPos. & Loc. — This delicate and beautiful species is 

 found in the Hamilton Group, on a broad slab literally cov- 

 ered with Crinoidea, Brachiopoda, and the following species 

 of Bryozoa. — [Illinois State Collection.^ 



8 L. 



8-9 t. 



Fenestella dilata, Prout. 



Bryozoum delicate, fan-shaped, about one inch long by one 

 and a fourth inches wide. 



Longitudinal rays irregular, not straight, rapidly diverg- 

 ing, branching often at the distance of about two-thirds of a 

 line apart, or at the top of every second fenestrule, curving 

 rapidly outward on both sides, plumose. 



Dissepiments thick, nearly as wide as longitudinal rays, 

 dilated at junction with the latter, arched and slightly de- 

 pressed near the borders. 



L'enestrules mostly broad oval, sometimes irregular and 

 arched where most expanded towards the border : 8 in lon- 

 gitudinal and 8 or 9 in transverse lines in a space of two 

 lines, indicating nearly equal dimensions in the fenustrular 

 spaces. 



Chalices or cells large, irregularly placed near each other 

 upon the two sides of a tine line or keel, usually two, some- 

 times one, and sometimes three to each fenestrule. 



Reverse unknown. 



Geol. Bos. & Loc. — This beautiful and delicate species was 

 found on the same slab with the F. nodosa, and belongs to 

 the Hamilton Group. 



Fenestella bifurcata, Prout. 



Polyzoum or Bryozoum, a fan-like expansion, with large 

 longitudinal rays and oscules distinctly visible to the nuked 

 eye. 



Longitudinal rays large, basaltiform, with a middle keel 

 and two rows of chalices ; bifurcating seldom towards the 

 base, but frequently and mostly in opposite series towards 

 the middle j four to five in each series. 



[April, 1866 ] 27 



