Spkciks of tiik Kkdkitk Group. 



173 



PlIRAGMODICTYA CATILLIFOUMIS, Whitfield (sj).). 

 Platk lxiv, Fios. 1-5; Platb lxv, Fios. 1. 2; Plate lxvi, Figs. 1-9; Plate lxvji, Fios. 1-4; 



Plate lxvui, Fios. 1-4. 



1881. 



Bull. No. 1, Amer. Mus. Nat. 



1882. 



1884. 



Dictyophyton catllUfm-me, Whitfield. 

 Hist., p. 18, pi. iii, fig, 1. 



Phragmodictya scyphus, Hall. Notes on the Family Dictyospongidse. 



Expl. pi. 17, figs. 12, 13; pi. 19, figs. 2, 3; pi. 20, figs. 1-6. 

 Phragmodictya catilUformis, Hall. Thirty-fifth Ann. Kept. N. Y. 



State Mus. Nat. Hist., p. 477, pi. 18, figs. 12-14; pi. 20, figs. 2, 3; 



pi. 21, figs. 1-6. 



Sponge sometimes of large size but usually of medium proportions ; subcyl- 

 indrical or with a somewhat flaring aperture ; base broad, slightly expanded, 

 its diameter increased by the projection of the periloph. General fonn stout, 

 the length being less than twice the median diameter. Specimens having the 

 aperture clearly retained show a slight contraction of the upper margin but it 

 is not fully determined whether this is a normal feature. 



The base is a very shallow obcone with a slightly eccentric apex ; its margins 

 appear to make an angle of about 1108 with the lateral walls of the cup, and 

 its converging surfaces to be gently concave except about the apex. 



Vertical walls of the sponge generally devoid of ornament except for a 

 series of irregularly disposed vertical ridges and elongate nodes. These lie at 

 subecpial intervals and occasionally a single ridge may be traced for nearly the 

 full length of the cup. The nodes seldom occur about the base, while they 

 multiply toward the top, the ridges sometimes being resolved int^ a series of 

 disconnected nodes, but frequently the ridge-like nodes appear in the inter- 

 spaces between the ridges, and without order or arrangement. At the edge 

 of the basal disc the ridges are abruptly transsected, making the margin 

 nodose, as it is in the genus Thysanodictya. The surface of the periloph 

 shows a more or less regular continuation of the ridges. The surface of the 

 basal obcone or disc is wholly smooth and in this respect is in marked distinc- 

 tion to the generally exposed or vertical walls of the cup. 



Mode of attachment. The convergence of the vertical spicular bands to 

 the apex of the basal diaphragm and the usual imperfection of this apex are 

 evidences of the attachment of the sponge at this point. Such attachment, 

 however, was restricted to the apex of this obcone, and though similar to that in 

 most of the Dictyosponges here considered, would have been ineflScient in 

 holding the sponge firmly in position. It is evident that important accessory 



