638 AQUATIC PHYCOMYCETES 



granules beside it in a clump, are readily seen. The first indication that the 

 spores are about to emerge is the gelatinization of the wall surrounding the 

 protruding spore mass. This takes about ten minutes, during which the mem- 

 brane increases to tour or five times its original thickness. About three to 

 four minutes before the spores emerge, those in the protrusion begin a rocking 

 motion which in a few seconds spreads throughout the sporangium; and in 

 a few seconds more the whole mass begins a slow motion which soon becomes 

 cyclic, so that the entire mass is moving round and round in the sporangium. 

 Suddenly at one end of the elongated, protruding mass the outer part of the 

 gelatinous membrane breaks and the inner part seems to dissolve, and 

 through this opening the spores rush out and swim away. In less than a 

 minute the entire gelatinous wall disappears and all the spores emerge except 

 for a few. These one by one find the slit, which has now become smaller, 

 and creep through to the outside. 



KEY TO THE SPECIES OF COELOMOMYCES 1 



Outer wall smooth, pitted, with or without faint striae or crinkles 

 Outer wall without striae or crinkles 



Outer wall with straight or diagonal rows of pits 1.5-3 \j. apart 



Pits large, 1.5-3 \i apart; resting spores 37 by 63 \i 



C. stegomyiae, p. 639 



Pits small, less than 1 .5 \x apart; resting spores 37-67 by 46-100 \l 



C. psorophorae, p. 640 



Outer wall with dispersed rounded or elongate pits, 2-4 \i apart 



C. punctatus, p. 640 

 Outer wall with faint striae or crinkles 



Outer wall with faint striae as well as pits; pits elongate, stellately 



arranged C. keilini, p. 641 



Outer wall with crinkles and dispersed pits C. africanus, p. 641 



Outer wall with bands or ridges; usually pitted 

 Outer wall with low bands 



Bands seven to ten, indistinct; wall sometimes pitted . . C. dodgei, p. 642 



Bands five to eight, narrow; wall very rarely pitted 



C. lativittatus, p. 643 



Outer wall with prominent ridges 



Ridges not anastomosing; similar in height, longitudinal 



Ridges numerous C. Indiana, p. 643 



Ridges four to six 



Ridges four, rarely more; pits transversely striate; wall not 

 unusually irregular 



Sporangia 12-21 by 19-40 \i 



C. quadrangulatus var. quadrangulatus, p. 644 



1 Key not strictly dichotomous. 



