g2 DiCTYOSPONGIDJS. 



Prismodictya spkctabilis, sp. nov. 



Plate xx, Fig. 5. 



Sponge large, long, rather slender; octagonal cross-section well-defined. 

 Prism-faces flat or, at times, slightly convex along the median line ; diameter 

 gradually increasing from the base to a point distant about one-fifth of the 

 entire length of the cup ; from this point upward the width does not vary 

 except for an abrupt contraction at the aperture. For a short distance near 

 the base the surface of the sponge is smooth and all evidence of the prismatic 

 faces obscured; the latter, however, rapidly become defined and are well 

 developed at about an inch from the basal extremity. The impression of the 

 reticulum upon the original internal cast shows a strong development of the 

 subordinate spicular bands, the coarser meshes being pretty generally 

 obscured. There are traces of elevated horizontal bands at intervals of about 

 10 mna. and these make nearly square quadrules with the prism-angles, and 

 subordinate squares or rectangles with the median line on each face. Toward 

 the lower end of the sponge the vertical bands are more prominent than else- 

 where. 



Dimensions. The specimen which has served as the basis of this descrip- 

 tion consists of two fragments, one representing the basal and the other the 

 upper part of the sponge, a portion of the median part being lost. Judging 

 from the slope of the sides the oiiginal length of the sponge must have been 

 about 275 mm. The full diameter, which is attained at 75 mm. fi-om the base, 

 is 37 mm. and this is maintained nearly to the aperture. The sponge shows a 

 slight curvature, but this is probably casual. 



Locality. In the upper beds of the Chemung group at Wellsville, Alle- 

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



Prismodictya parallela, Hall (sp.). 



Plate xix, Fig. 4 ; Plate xx, Fig. 6 ; Plate xxi. Figs. 8, 9 ; Plate xxxv, Fig. 9. 



1884. Dictyophytoii parallelmn, Hall. Thirty-fifth Ann. Rept. N. Y. State 

 Mus. Nat. Hist., p. 471. \ 



Sponge prismatic, elongate, slender, very gradually enlarging; prism- 

 faces slightly convex, divided by a median vertical ridge which is somewhat 

 elevated. Surface crossed by elevated horizontal bands at intervals varying 

 from 8 to 10 mm.; making low nodes at their intersection with the prism- 

 angles. The subordinate division of the reticulum is normal. 



