SPONGI^. 



157 



No. 495. [1164. Cast]. Brachio- 

 spongia digitata, Oweu. 



This large and remarkable fossil 

 sponge, with eleven beautifully radiat- 

 ing and recurved hollow branches, is 

 from the Lower Silurian, Franklin 

 Count}^ Ky. 



According to Mr. Beecher the num- 

 ber of branches or arms in this species 

 vary from 8 to 12, and the specimens 

 range in size from 3^ to 11 inches in 

 diameter. 



Size of thit, specimen, 11 x 11. 



No. 496. [1165, Cast]. Coeloptychium agaricoides, Coklf. 



These mushroom-like Sponges liave the 

 upper surface marked by pores in trans- 

 verse lines, and the lower one rayed. 

 From the Chalk, Haldem, Westphalia, 

 and now in the Ward Collection of the 

 University of Rochester. 



No. 497. Cryptozoon protiferum, Hall. 



This sponge was long known as Stromotopora rugosa, and was assigned to 

 the Calciferous Epoch, instead of the Potsdam as at present. Saratoga, N. Y. 



No. 498. Dictyophyton nodosuni, Hall. 

 Chemung Group, Bath, Steuben County, New York. 



No. 499. Dictyophyton tuberosum, Hall. 



This interesting sponge was formerly supposed to be a plant, 

 as the name signifies. It is the internal cast of a sponge which 

 had a network somewhat like the living Euplectella. The 

 genus is known by eight or ten species. In the present species 

 (as also in D. nodosum) the body expands at intervals, and is 

 protruded into tubercles or nodes, with a longitudinal axis and 

 moderate elevation. From the Chemung Group (Upper De- 

 vonian), of Steuben County, N. Y. Size, 7 x 5. 



No. 500. [1168, Cast]. 



Polypothecia dichotoma, 

 [Benett. 



This genus is allied to ScypMa. The species presents 

 considerable diversity of shape. This beautiful speci- 

 men shows several branches springing from one root. 

 Upon breaking these stems transversely, sections of 

 parallel longitudinal tubes are exhibited as in Siphonia. 

 From the Upper Greensand, Warminster, England. 



Size, 7x4. 



