86 DlCTTOSPONGID^. 



Prismodictya cortnia, sp. nov. 



Plate xvii, Fig. 11. 



Sponge large, the incomplete specimen on which the species is founded 

 indicating a greater size than is attained by any other known representative 

 of the genus; expanding with some rapidity from the base and contracting 

 toward the aperture. Prism-faces clearly defined, some of them with a 

 low elevation in the median line, their edges scarcely elevated into ridges. 

 Surface reticulated by spicular bands of subequal size, which, by intersection, 

 form quadrilles about 6 mm. square ; a size which is uniformly maintained 

 over the entire surface, except for a slight diminution toward the base and 

 summit. This is the quadrule which impresses one as being the most promi- 

 nent, though a combination of sixteen of these, four on each side, covers one- 

 half the width of each prism-face. The quadrules are subdivided by three 

 sets of spicular bands. 



This sponge attained a size equal to that of P. clinanea, but is readily dis- 

 tinguished from that species by its more sharply prismatic surface. Prismo- 

 dictya clioanea is very obscurely prismatic and in this respect approximates the 

 normal condition of Dictyospongia. 



Dimensions. Length of the specimen described, 140 mm.; probable 

 original length not less than 240 mm. ; diameter at the lower end 90 mm. ; at 

 the middle 110 mm. ; at the top 90 mm. 



Locality. In the upper beds of the Chemung group. Alma, Allegany 

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



Prismodictya filitextilis. Hall (sp.). 



Plate xxi, Fio. 7 ; Plate xxvii, Pig' 4. 



1873. Dictyophyton JiUtextile, Hall. Sixteenth Ann. Kept. N. Y. State Cab. 



Nat. Hist., p. 88, pi. iv, fig. 5. 

 1884. Dictyophytan fiUtextile, Hall. Thirty-fifth Ann. Kept. N. Y. State 



Mus. Nat. Hist., p. 470. 



Sponge small, slender, very gradually enlarging. Surface obscurely 

 prismatic, the prism-faces being convex. 



Reticulum, extremely fine ; a very sharp external cast shows that the 

 major quadrules are formed by the intersection of horizontal bands with the 

 prism-angles, slight nodes being made at these points. These quadrules measure 

 about 8 by 9 mm., being somewhat higher than wide. The sub(.)rdiuate 

 reticulation, however, usually obscures the larger meshes. 



