262 FRESH-WATER BIOLOGY 



151(150) Colonies not of branching tubes 152 



152 (153) Colony in a gelatinous mass; variable in shape, thread-like, discoi- 

 dal or round, hollow or sac-like. Individuals with tw^o 



equal flagella Spongomonas Stein. 



Representative species Spongomonas discus Stein 1878. 



Colony discoidal, gelatinous mass granular; zooids subspheroidal. 

 Flagella two or three times the length of the body. Length of 

 zooids 8 Ai. Fresh water. 



Fig. 431. Spongomonas discus. X lOO. (After Biitschli.) 



1 53 (152) Colony formed of jelly-like tubes, closely approximated; individuals 



as in Spongomonas Rhipidodendron Stein. 



Representative species. 



Rhipidodendron splendidum Stein 1878, 



Tubules forming an erect branching colony. Zooids ovate or ellipti- 

 cal, usually in the distal extremity of the tubules. Flagella equal, twice 

 the length of the body. 



The tubes being hollow are probably secreted or excreted from the 

 entire surfaces, rather than the posterior extremities of the zooids. 

 The tubes are usually rusty-brown in color and have a granular appear- 

 ance. Sometimes as many as two hundred tubes are bound together 

 in one mass. 



Length of body 12 //. Fresh water. 



Fig. 432. Rhipidodendron splendidum. X 250. (After Stein.) 



154(147) Individuals not imbedded in a gelatinous mass 155 



155 (156) Forming spherical colonies. About fifty individuals held loosely 

 together, each with a delicate membrane, often spiny. Fla- 

 gella two, unequal Synura Ehrenberg. 



Representative species Synura uvella Ehrenberg 1833. 



Membranes pyriforn,, often with pKJSterior stalk-like pro- 

 jections; surfaces spiny. Zooids nearly filling membranes. 

 Color bands two, extending along the lateral borders. Length 

 of body 30 fi. Pond water. 



Fig. 433. Synura uvella. X 6cx3. (After Conn.) 



