Species of the CnEMirNo (troup. 89 



species cited, but are much less conspicuous than in those. Though the 

 specimen described is incomplete, it is evident that the sponge rapidly 

 narrowed from the line of these nodes upward. 



The reticulum is as in other prismatic species. Along the middle of each 

 prism-face is a conspicvious spicular band and the major quadrules which this 

 forms with the prism-angles are clearly divided by four series of lines, all of 

 them distinct without any one series obscuring the rest. 



Di'mensions. The single specimen of this form observed has a length, 

 covering only the body of the cup, of 125 mm. ; its width at the fractured 

 base is 20 mm. and across the swollen body, 110 mm. 



Locality. From the upper Chemung sandstone at Scio, N. Y. (Collec- 

 tion of E. B. Hall.) 



Pbismodictya cercidea, sp. nov. 



Plate xx, Fig. 1-3 ; Plate xlii, Fig. 3. 



Sponge small, fusiform, with well defined prism-faces which are flat or 

 somewhat concave ; rather gradually expanding for somewhat more than one- 

 half its length, where its greatest diameter is attained, thence tapering ^\•ith 

 greater rapidity to the aperture which is contracted and very small. At the 

 apex the eight prismatic faces are distinctly defined and, at the summit, these 

 faces so nearly meet that in some instances it is impossible to determine which 

 is the basal and which the apertural extremity. At the greatest expansion of 

 the sponge, near the middle, there are thickenings or elongated nodes upon 

 the prism-angles. 



Meticulam fine ; prism-faces devoid of prominent vertical spicular bands, 

 while the horizontal bands are numerous but not conspicuous. The largest 

 quadrule, measuring 4 mm. on each side, is frequently repeated, but the minor 

 subdivisions of the net-work prevail on all the specimens observed. 



Dimenffiom. Of three entire individuals one measures 62 mm., and two 

 55 mm. in length. All are somewhat compressed, but agree in having a 

 greatest diameter of 22 mm. The apertural diameter is not more than 2 or 

 3 mm. 



The presence of low nodes on this species shows its relationship to 

 P. ptionia and P. dtlmra. To the latter P. cercidea is very closely allied 

 but does not possess its long slender base. 



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

 gany county, N. Y., associated with the lamellibranch, Sphenotais contraA;tu8. 

 (Collected by E. B. Hall.) 



