SpEOIES ok the ClIKMIJ.Vii flKOirP. 81 



IS undoubtedly a matter of difference in retention. Over the surface of these 

 markings, whether ridges or grooves, the meshes of the reticulum are distinctly 

 seen. There is so close a resemblance in these features to tubes of aiuielids 

 or those left by certain boring sponges as to justify the suggesticju that we 

 have here an indication of parasitism or commensalisni of such boring or 

 tubicolous animals with the Dictyosponges. On Plate ix (fig. 2) is given a 

 figure of Hydmceras tuberosum var. glosmna which very distinctly shows 

 similar vermiform markings. 



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

 specimens were derived from a locality now unknown, in Cattaraugus county. 

 The species has been found in some abundance at Wellsville and Fnendship, 



Allegany county, N. Y. 



Prismodictya baculum, Hall (sp.). 



Plate xviii, Figs. 1-3. 



1884. Dictyophyton baculum, Hall. Thirty-fifth Ann. Rept. N. Y. State 

 Mus. Nat. Hist., p. 471. 



Sponge prismatic, distinctly octagonal, the prism-faces being flat or very 

 slightly concave; form very gradually expanding from the base for about 

 one-half its length, thence enlarging rapidly and again contracting toward the 

 aperture. 



Heticulum. The primary quadrules measure about 7 mm. on the edge, 

 but distinctly enlaige in size from below upward. Each quadrule is bounded 

 vertically by the band upon the prism-angle and by one medially dividing the 

 prism-face. The horizontal bands have left sharply defined impressions upon 

 the surface of the cast. The character of the reticulation is, throughout, 

 essentially the same as that of Prismodictya Oonradi, but the species differs 

 from the latter in its more gradual expansion from the base upwai-d and the 

 absence of the peculiar nodes of that species; it differs from P. parallela 

 in its distal expansion and the absence of elevated horizontal ridges with 

 nodiform intersections. 



Dimensions. The length of the best preserved example is 60 nun.; this 

 specimen is probably but slightly imperfect at the aperture, though somewhat 

 more at the basal extremity. Its diameter at the lower end is 26 ram.; at the 

 greatest width, 43 mm., and at the upper end, 39 mm. 



Locality. In the Chemung group at Wellsville, Allegany county, N. Y. 



