﻿Neiv Genus and Sjjecies of Cystideans. 



287 



Description of a New Genus and Species of Cysti- 



DEANS FROM THE TrENTON LIMESTONE AT (3tTAWA.^ 



By J. r. Whiteaves. 



ASTROCYSTITES OtTAWAENSIS. 



Fig. 2. 



Fig. 3. 



Figs. 1-3. Astrocystites Ottaicaensis. Fig. 1. Side view of 

 a nearly perfect specimen, shewing the small plates surrounding 

 and perhaps covering the anus, on the left side of one of 

 the ambulacral areas, at A, and the peculiar sculpture of part 

 of the calyx, natural size. Fig. 2. Summit view of the same 

 specimen, also of the natural size. Fig. 3. Radial plate on the 

 left of the anal region of another specimen, twice the natural 

 size, to shew the peculiar shape and sculpture of this plate, also 

 the overlap by the distal portion of one of the ambulacral areas 

 above, and the modification of the upper margin of the plate 

 on the anal side : A — relative position of the anus. 



Body or " crown" of the organism globose, almost 

 spherical but narrowing rapidly below into a very short, 

 slender column or stem, and somewhat five-sided as seen 

 from above. 



Calyx or dorsal cup broadly conical and entire below 

 the midheight, but divided above into five large, pointed 

 and slightly incurved, sepaloid lobes, with rather oblique 

 and slightly convex sides, by the decurrent portions of the 

 ambulacral areas. The greater part of one of these lobes, 

 as seen at A, in Fig. 1, is occupied with a cluster of 

 minute plates, which surround and either partially or 

 wholly cover the anal opening. 



1 Coininunicated by iieriiiission of the Director of the GeologiCcal Survey. 



