128 DlCTYOSPONGID.15. 



3 to 5 ram. At the intersection of these lamellae, somewhat thickened nodes 

 or tufts are formed which extend beyond the edges of the lamellae themselves. 

 The aiwrture appeai-s to be without evidence of a marginal tuft. The basal 

 disk is somewhat thickened and bears ridges at the margins, but the character 

 of its surface and that of the peripheral frill is not well shown. 



Dimensions. Four examples of this species are preserved upon a single 

 slab of sandstone. Of the best two of these, one measures 100 mm. in length ; 

 diameter at the base (exclusive of marginal expansion), 55 mm.; at the 

 aperture, 53 mm. ; at the narrowest portion of the cup, 37 mm., and, with the 

 surface lamellae, 46 mm. ; the other, a much more slender cup, has a length of 

 120 mm. (incomplete), an apertural diameter of 30 mm. and a narrowest diam- 

 eter of 22 mm. 



This species is distinguished in its stouter form, from Thysarwdictya 

 rudis, and in its more slender form, from T. Mlwi/i-IIalli, by the smaller 

 size of its primary quadrules. 



Locality. In the upper beds of the Chemung sandstones, associated with 

 Camarotcechia and Leptodesimi, Scio, Allegany county, N. Y. (Collection of 

 E. B. Hall.) 



Thysanodictya rudis, Hall (sp.). 



Platk XIX, Fig. 7 ; Platk xxiii, Figs. 1-6. 



1863. Diet yophy ton rude, Hall. Sixteenth Ann. Rept. N, Y. State Cab. Nat. 

 Hist., p. 90, pi. V, fig. 3. 



1884. Dictyopliyton riide, Hall. Thirty-fifth Ann. Rept. N. Y. State Mus. 



Nat. Hist., p. 469. 

 1890. Dictyopliyton scitum, Hall.' Ninth Ann. Rept. N. Y. State Geologist, 



p. 58; Forty-third Ann. Rept. N. Y. State Museum, p. 260. 



Sponge moderately large, cylindrical. Base subtruncate, closed by a 

 broadly obconical diaphragm. Surface sharply divided by a series of vertically 

 elongate (piadrangles which, in the middle portion of the original specimen, 

 appear to be all of approximately the same size. Each of the quadrules of the 

 first order eniljraces four of these rectangles and measures, on an average, 

 1 5x18 mm. Toward the base of the cup these primary quadrules are more nearly 

 square. The bands of the first and second series form low nodes at their in- 

 tersection and both the vertical and horizontal seiies are produced into erect 

 lamellae which may extend outward from the surface for a distance of from 

 3 to 5 mm. The third, fourth and fifth series of spicular bands are seldom 

 clearly developed, being to some extent obscured by the ultimate division of 



