90 DieryospoNGiDA 



PRisMODicryA ciTHARA, sp, nov. 



Plate xxxv, Fiob. 1-3; Plate xxxvi, Fig. 5. 



Sponge of small size, with a very gently expanding, stalk-like basal 

 portion which, at about mid-length of the sponge rather abrui)tly widens, 

 very gradually tapering toward the contracted aperture. 



The lower part of the sponge is more or less distinctly prismatic and the 

 faces and angles are retained over the expanded portion. Where the gi-eatest 

 width of the cup is attained, low, elongate nodes are developed upon the 

 prism-angles. These are of the same character as those already described for 

 P. cei'ciJsa and P. ptionia, being very much elongated vertically and scarcely 

 thickened. As in the species cited, also, they appear in but a single trans- 

 verse row. By distortion, the nodes in one of the specimens figured are made 

 to appear of exaggerated size ; usually they are low and obscure. 



The reticulum is fine, as in P. cercidea, and the chief difference in these 

 species is in the extended basal portion of that under consideration. 



Dimensions. A large, slightly distorted but nearly entire specimen is 

 73 mm. long, 7 mm. wide near the base, and 22 mm. wide where most expanded. 

 This seems to be exceptionally large size and a considerable number of others 

 indicate prevailing less size, a normal small specimen having a length of 

 39 mm., a width at the base of 4 mm. and a greatest diameter of 15 mm. 



Locality. In a compact siliceous sandstone of the upper part of the 

 Chemung group at Scio, N. Y. (Collection of E. B. Hall.) 



Prismodiotya narthecia, sp. nov. 



Platk XXXV, FiQS. 4, 5. 



This small species is allied to P. cithara and P. cercidea; more closely 

 to the former, from which it differs in its more slender form, and though it is 

 not without the median expansion of that species, yet this is very much less 

 in degree and bears only the faintest suggestions of nodes. The slender 

 base which it possesses in common with P. cithara, will distinguish it from 

 P. cercidea. 



But a single specimen of this little sponge has been observed. This 

 measures 44 mm. in length, 3 mm. in width at the base, 9 mm. in width Avhere 

 broadest, and 5 mm. across the aperture. 



Locality. In the upper beds of the Chemung group at Scio, N. Y., asso- 

 ciated with the preceding species. (Collection of E. B. Hall.) 



