Species of the CriEMiiNo Gnoirp. 85 



expansion, which is 70 mm. from the upjw end. A somewhat smaller but 

 more complete example has a length of 185 mm. ; an apical diameter of 15 mm. ; 

 a greatest width of 60 mm. and a subapertural diameter of 50 ram. 



This species bears some similarity to Prismodlctya haculum in the expan- 

 sion of the cup above the middle, but differs in its proportionally less slender 

 form and its persistently greater size. A number of specimens from different 

 localities all show the specific characters described. 



Localities. In the upper beds of the Chemung group, at Scio and 

 Almond, Allegany county, and Ischua and Olean, Cattaraugus county, N. Y. 

 (Collection of E. B. Hall.) 



Pbismodictya choanea, sp. nov. 



Plate xix, Figs. 1-3; Platb xxvii, Fia. 5 ; Plate xxxv, Fig. 6. 



Sponge large, elongate, rapidly expanding from the base, attaining a 

 greatest dianieter above the middle, thence somewhat abruptly contracting to 

 the aperture. Median transverse section rounded octagonal. Surface smooth 

 about the base, thence upward becoming faintly prismatic, these prism-faces 

 again becoming obscure and finally obsolete toward the summit. 



Reticulum fine ; composed of quadrules the largest of which, over the 

 basal portions of the cup, are bounded vertically by the edges of the prism- 

 faces, crossed by horizontal bands at subequal distances. This makes of the 

 main quadrules, squares measuring about 30 mm. on each side. These large 

 areas are distinctly subdivided by one inferior series of bands, and each of 

 these, in its ultimate division, contains approximately 256 meshes. 



Toward the median portion of the sponge the prismatic faces become 

 somewhat more obscure and the division into the quadrules of the first and 

 second order more sharp. 



Dimensions. This description is based upon specimens which represent 

 only the lower portion of the sponge and we are not justified in inferiing the 

 character of the upper part except that while the species may assume the 

 proportions of Prismodictya corynia in its later growth, it probably does not 

 become so strongly prismatic as does that species. On the other hand, it is 

 easy, from the obscurity of their prism-faces, to confound such specimens as 

 those figured, with the Dictyospongia Almondensis, the fragments of which, 

 occuring in great numbers in the grey sandstone at Almond, sometimes show 

 faint prismatic divisions which are wholly the result of compression. 



Localities. In the upper beds of the Chemung group at Ischua and 

 Olean, Cattaraugus county, N. Y. (Collection of E. B. Hall.) 



