SPONGES. 271 



ZlTTELELLA INOSCULATA U. & E. 

 PL V. Figs. 6-6a. 



Sponge pestle-shaped, the stem large, subcylindrical, the upper 

 portion expanded, with the margin narrowly rounded into the 

 convex upper surface. The vertical channels on the sides of the 

 sponges are very irregular and frequently united. The inter- 

 spaces vary in width from one to three mm., and the number 

 of channels in a space 10 mm. wide, from four to seven, while 

 the average number is about five. The central portion of the 

 upper surface is abruptly depressed, the depression stellate, and 

 exhibiting at the bottom the mouths of from four to eight 

 cloacal tubes. The radiating furrows are wavy, bifurcate and 

 inosculate freely with each other, and from 0.5 mm. to 0.8 mm. 

 in width. The interspaces which are narrow wedge-shaped in 

 the region about the cloacal depression, vary in width from 0.2 

 mm. to 2 mm., being widest at the margin. 



Height of a medium sized specimen, 33 mm.; diameter of stem 

 varying from 14 to 18 mm.; height of same 21 mm.; diameter 

 of upper portion, about 27 mm. Another example is about 25 

 mm, in diameter; height of expanded upper portion 10 mm.; 

 diameter of stem where it is broken from the body of the sponge, 

 about 11 mm. The form of this specimen appears to have been 

 very much like that of Z. typicalis var. pistilliformis, figured on 

 the same plate with this species (PI. V, fig. 4,). 



The distinguishing characters of the species are found in the 

 wavy and inosculating surface channels, and the generally wider 

 interspaces. The form of the sponge approximates to that of 

 Z. typicalis var. pistilliformis, but none of the four specimens 

 are so much expanded above. A comparison of their respective 

 surface channeling^ will readily distinguish them. 



Position and locality: Twenty-five feet above the base of the 

 Trenton limestone near Dixon, 111. 



EDRIOSPONGIA nov. gen. 



Sponge massive, lobate, attached by a broad base, with the 

 sides irregularly indented. Canal system irregular, consisting 



