124 DlCTYOSPONGID^. 



Retiaulum. The surface is covered with the fine reticulations of the 

 ultimate spicular bands, but these do not obscure the coarse ridges of the 

 primary bands. The latter form quadrules which are somewhat broader than 

 long, and measure on the average 17x15 mm. The vertical bands appear to 

 be somewhat stronger than the primary horizontal series, and this gives a 

 slight subprismatic aspect to the surface. 



This sponge is not greatly iinlike Clathi'ospongia fenestrata ; a more 

 complete knowledge of both may demonstrate their identity ; with our present 

 information however, O. tomacidum appears to have been a rather more 

 slender cup, with a coarser primary reticulation. 



A small fragment of a second specimen retains the definition of the 

 surface characters much more sharply. Here each of the principal quadrules 

 is divided by a subordinate pair of spicular bands, which are nearly as promi- 

 nent as those of the first order, and the finer subdivision is clearly shown in its 

 ultimate division, each principal quadrule containing 256 minimum quadrules, 

 produced by the intersection of five series of spiciilar bands. 



Locality. From the upper part of the Chemung group ; in a loose block 

 at Alfred, Allegany county, N. Y. 



ClATHROSPONGIA (?) IRREGULARIS, Hall (sp.). 

 Plate xv, Figs. 6, 7. 



1884. Dictyophyton irregulare, Hall. Thirty-fifth Ann. Kept. N. Y. State 

 Mus. Nat. Hist., p. 470. 



Sponge small, gently tapering, very faintly subprismatic. In the original 

 specimen, which is an internal cast, these prism-faces are much obscured, 

 partly by compression and partly, also, by the surface reticulation. 



The surface is divided into major quadrules by transverse bands equidis- 

 tant with the edges of the prism-faces, thus forming squares measuring about 

 9 mm. on a side, at each of the angles there being a low node. All of these 

 characters are, for the most part, very obscure, but sufiicient is preserved to 

 show that, in its original condition, the sponge was divided into strong quad- 

 rules as described, these being tufted at their angles. The subordinate 

 reticulation of the surface is normal. 



Dimensions. The single example of this species is complete at neither 

 extremity, though probably little is wanting at the upper end, and its basal 

 extent is indicated by the slope of the sides. The length of the part retained 

 is fi5 mm. ; the original length was probably not more than 75 mm. The 

 greatest diameter of the cup is 25 mm. 



