no DlCTYOSPONGIDiF,. 



there are hut three transverse rows oi nodes, and in the lowest row but three 

 of the normal eight nodes are distinctly developed, three others are merely 

 suggested while two are absent. In the second and third rows all nodes are 

 present but are unetjually developed. The fi'agment of a second and some- 

 what larger specimen shows four transverse I'ows of nodes. All of these 

 nodes are small and are elongated by the prism-angles on \\hicli they lie. 

 Their presence does not materially obscure the fundamental prismatic form of 

 the s2)onge. 



In full development each node is prominent, its height ecpialling about 

 one-fourth of the diameter of the cup. They are directed gently downward 

 and distinctly tufted. The upper or apertural portion of the sponge is smooth 

 for a considerable distance and noticeably expanded. The margin is regular. 



RetiGulmn fine, the principal spicular bands being those at the angles of 

 the prism-faces, with a corresponding horizontal series dividing the constric- 

 tions between the nodes. The remainder of the net- work is subequally 

 divided into quadrules measuring about 1 mm. on each side, and these are 

 again divided by a single series of bands. 



Dimensions. An entire specimen has a length of 60 mm., a greatest 

 width of 20 mm. and an apertural width of 17 mm. Other specimens indicate 

 about the same proportions. 



A very interesting feature of this species is the retention of a pronounced 

 prismatic surface, the late appearance of the nodes and their feeble develop- 

 ment. Other species demonstrate the relationship of Hydnoceras to Prismo- 

 DicTYA, but in none is the connection so clearly shown as in this later and 

 probably degenerate form. 



Localities. A rare species, which has been observed only in the 

 higher beds of the Chemung group, in a very compact green sandstone at Scio 

 and Wellsville, N. Y. (Collection of E. B. Hall.) 



Hydnoceras eumeces, sp. nov. 



Plate xii, Figs. 1-3. 



This is a very large species vnth narrow, elongate, sharp nodes and 

 narrow prism-faces. The original specimen has been greatly compressed 

 vertically, but shows features Avhich are not possessed by the other species of 

 the genus. This is indicated, first by the dimensions of the fossil, the internal 

 cast having a diameter of 180 mm., while the distance across the cup as indi- 

 cated by the external impression, was about 225 mm.; a size not surpassed in 

 any known specimens of this genus. The example affords no conclusive 



