412 TRANS. OF THE ACAD. OP SCIENCE. 



POLTPOUA IMBRICATA, PrOllt. 



Bryozoum a funnel-shaped expansion, about one inch long 

 by one and a quarter inches wide, having a distinct, flatten- 

 ed, irregular, rounded, hollow pedicle, with a round, narrow 

 neck. Chalices on the inner face. 



Longitudinal rays nearl} 7 straight, on reverse being some- 

 what smaller than the dissepiments, seldom branching, 

 branching about two lines apart, minutely granular on 

 reverse or outer aspect of the bryozoum. 



Dissepiments short, broad, much dilated at junction, finely 

 granular in reverse. 



Fenestrules mostly round or slightly oval (5 long.-6 trans, 

 in space of 2 lines), deeply and conically depressed on re- 

 verse ; irregularly round or oblong oval on medallion face, 

 sometimes becoming obliterated, and opening obliquely 

 upwards to the plane of expansion. 



Chalices small, moderately long, tubular, imbricate, 

 placed very obliquely, looking upward and outward to the 

 plane of expansion, somewhat irregular, but generally in 

 three to four lines upon each ray, which seems to swell 

 more or less above each fenestrule; mouths, where seen, 

 thin, round, and slightly raised. 



This beautiful and delicate species is characterized by the 

 obliquity of the chalices to the plane of expansion. The 

 chalices are more or less irregular, less than their own 

 diameter apart hoi'izontally, and twice their diameter 

 apart longitudinally ; often appearing to be imbricated when 

 we look down obliquely upon them. 



Geol. Bos. & Loc. — Mountain Limestone, Indiana. 



POLYPORA RIGIDA, PrOUt. 



Bolyzoum a semicircular, flat, flabelliform expansion, ra- 

 diating from a central axis. 



Longitudinal rays small, sharply defined ; straight, rigid 

 and wire-like upon the reverse; seldom branched, some- 

 times anastomosing; mostly branching from dissepiments, 

 by which the fenestrules are much diminished in size. 



Dissepiments, on the reverse, small and sharply defined; 

 mostly opposite, in straight or curved lines ; sometimes 

 alternate. 



Fenestrules large, longer than broad, mostly quadrangu- 

 lar, sometimes rounded at angles and more or less irregular 

 in size. On the medallion face the fenestrules are crowded 

 by the growth of the cells, and are more or less oblong oval. 



Retepora Hamiltonensis, Proiit. 



Bryozoum a broad, funnel-shaped expansion, with longi- 

 tudinal ra} T s frequently branching and rapidly diverging so 

 as to give an explanate or flat form to the funnel, which 

 only shows the reverse or lower surface. 



