182 ILLINOIS BIOLOGICAL MONOGRAPHS [420 



32(33) Shell-valves shorter (sutural diameter: breadth = 1:1.6) 



Ceratomyxa coris Georg6vitch 1916 (72) 



33 (32) Shell-valves longer (sutural diameter : breadth = 1 :2 . 6) 



Ceratomyxa herouardi Georgevitch 1916 (72) 



34(23) Shell-valves as3Tmnetrically built 35 



35(40) Spore arch-shaped in front view 36 



36(37) Sutural diameter equal to one-fifth of breadth; sutural diameter lO/t, breadth 

 50m 



Ceratomyxa globulifera Thelohan 1895 (67) 



37(36) Sutural diameter more than one-fifth of total breadth 38 



38(39) Spore: breadth shorter; sutural diameter 14m, breadth 17m 



Ceratomyxa abbreviata Davis 1917 (76) 



39(38) Spore: breadth longer; sutural diameter 12 to 15m, breadth 45 to 50m 



Ceratomyxa reticularis Thelohan 1895 (68) 



40(35) Spore straight 41 



41(42) Sutural diameter 11m, breadth 27m. Trophozoite alwajrs roimded 



Ceratomyxa amorpha Davis 1917 (78) 



42(41) Sutural diameter 6m 43 



43(44) Trophozoite with active pseudopodia. Spore: sutural diameter 6m, breadth 



22 to 24m 



Ceratomyxa undtdala Davis 1917 (79) 



44(43) Trophozoite with inactive pseudopodia. Spore: sutural diameter 6m, breadth 

 31m 



Ceratomyxa inaequalis Doflein 1898 (68) 



45(22) Sutural diameter less than one-fifth of total breadth 46 



46(49) Breadth of Sf)ore equal to or greater than 50m 47 



47(48) Shell-valve tapering gradually toward distal end; sutural diameter 8m, breadth 

 50 to 56m. Trophozoite usually elongated pyriform 



Ceratomyxa mesospora Davis 1917 (73) 



48(47) Shell-valve rounded at distal end; sutural diameter 6 to 7m, breadth 50m. Tro- 

 phozoite usually rounded or irregular form; size small 



Ceratomyxa aggregate Davis 1917 (79) 



49(46) Breadth of spore smaller than 30m SO 



50(51) Trophozoite ordinarily spherical, diameter not exceeding 16 to 20m; protoplasm 

 extremely pale looking. Spore : sutural diameter 5m, breadth 25 to 30m. 



Ceratomyxa pallida Thelohan 1895 (67) 



51(50) Trophozoite pyriform with a long posterior process; movements by wavelike 

 motion of ectoplasm; also active backward movements of pseudopodia. Spore 

 asymmetrically built; sutural diameter 5m, breadth 24 to 28m 



Ceratomyxa agglomerata Davis 1917 (77) 



52( 1) Spore variable in size and form 53 



53(54) Variation in number of shell-valves conspicuous; sutural diameter 5m, breadth 

 25m 



Ceratomyxa truncata Thelohan 1895 (67) 



54(53) Variable in size and form of spore, but not in niunber of shell- valve 55 



55(60) Trophozoite more or less definite in shape 56 



56(59) Trophozoite usually pyriform 57 



57(58) Trophozoite disporous. Spore: sutural diameter 7 to 9m, breadth 15 to 38m 



Ceratomyxa lunata Davis 1917 (76) 



58(57) Trophozoite monosporous or disporous. Spore: sutural diameter 5 to 6m, 

 breadth 18 to 25m 



Ceratomyxa monospora Davis 1917 (78) 



Niunbers enclosed in parentheses refer to the page of the article on which is found the description of the species 

 named. 



