272 . PALAEONTOLOGY OF ILLINOIS. 



of closely arranged radiating canals, connected by tortuous 

 vertical canals passing through them. Minute canals, formed 

 by the arrangement of the spicules in linear series, traverse the 

 sponge in a direction parallel with the radiating canals. When 

 perfect the sides of the sponge are covered with a minutely 

 porous dermal layer. When this is removed the irregularly 

 arrayed apertures of the radiating canals are exposed. Spicu- 

 lar structure between the canals, of unequal thickness, usually 

 narrow. 



The distinguishing characters of this genus may be summed up 

 as follows: (1) The massive form, (2) broad base, (3) absence 

 of stellate oscula and vertical cloacal tubes, and (4) the irregular 

 arrangement of the canals, when compared with those of An- 

 thaspidella and Zittelella. From Streptosolen the genus is 

 separated by the three peculiarities first noted, as well as by 

 the smaller and less tortuous radiating canals. 



EDKIOSPONGIA BASALIS U. & K. 



PL VI, fig. 1. la, lb, lc. 



Sponge massive, irregular in outline, and attached to foreign 

 bodies by a broad base; the sides are irregularly and often 

 deeply indented, so as to impart to the mass a rudely pillared 

 aspect. Upper surface with irregular depressions, but without 

 oscula save those of the radially arranged vertical canals. 

 These usually alternate with the radiating canal furrows, and 

 form close series between two of the latter. Five or six mouths 

 occur in the length of 5 mm., while the diameter of each is 

 about 0.6 mm. 



Upon grinding the surface it will be noticed that the radiate 

 furrows are replaced by rows of vertical canal apertures, and 

 the series of the latter by radiating canals. This changing 

 from one to the other repeats itself if the grinding is continued, 

 and proves that the two sets of canals pass through each other, 

 and are alternately developed at the surface. The sides of the 

 sponge, when the dermal layer is removed, often show the sub- 

 Circular mouths of the radiating canals arranged in irregular 



