SpECIKS of TliE ClIKMUNO GuOUP. 87 



Dimensions. The original specimen has a length of 60 mm., a width at 

 the lower end of 11 mm., and at the upper end of 15 mm. Eswentially the 

 same proportions are exhibited by other specimens. The species is distin- 

 guished by the obsolescence of the prism-faces, its fine reticulation and usually 

 small size. 



Localities. In the upper beds of the Chemung group. Tlie original 

 specimen is from some locality, now unknown, in Steuben county; others 

 have been found at Wellsville, Allegany county, N. Y., by Mr. E. B. Hall. 



Pbismodictya banano, sp. nov. 



Plate xvii, Fig. 2. 



Sponge elongate and quite slender; regularly expanding for nearly one- 

 half its length, thence very gradually decreasing in width to the aj^erture ', 

 distinctly prismatic ; prism-faces slightly concave. 



Heticulum fine, the principal quadrules apparently being bounded by the 

 prism-angles and subequidistant horizontal bands. 



Dimensions. The original specimen, which is complete at the apei'ture 

 but slightly broken at the basal extremity, has a length of 120 ram. \vith a 

 probable original length of 135 mm. The diameter at the lower end is 

 11 mm.; just below the middle, 20 mm., and at the aperture 13 mm. 



This species is much more slender than any other of the forms of 

 Prismodictya except P. aniicitice, and as the latter is quite distinct in size 

 and contour, the form will be readily distinguished. 



Locality. In the upper part of the Chemung group at Scio, Allegany 

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



Prismodictya amiciti^, sp, nov. 



Plate xxxvi, Figs. 2-4. 



Sponge small, slender, graceful, and cigar-shaped, being somewhat 

 broadest toward the lower end just above the basal point, thence iipward 

 tapeiing very gradually and regularly to the aperture. In respect to this 

 expansion of the lower part, the species resembles P. telnm, but is a much 

 more slender sponge than that. 



The prism-faces are not very sharply defined, so that without the actual 

 obliteration of the interfacial angles, these are rendered obscure by a general 

 convexity of the surface, which characterizes the entire length of the sponge. 



Beticulum as in other forms of this genus. 



