74 ILLINOIS BIOLOGICAL MONOGRAPHS [312 



Vegetative form rPyriform, elongate. Numerous fine filiform pseudo- 

 podia at anterior end. Progressive movements rapid. Body colorless and 

 transparent. Ectoplasm clear and homogeneous. Structure of endoplasm 

 highly variable, in majority of trophozoites filled with transparent homo- 

 geneous spherules. Small fat globules at the anterior end. In some sporu- 

 lating individuals, the endoplasm shows vacuolated structure without any 

 spherules, usually, however, sporulating trophozoites exhibit well-defined 

 spherules. The spherules or vacuoles, as the case may be, are separated by 

 a thin layer of distinctly granular endoplasm containing numerous rod- 

 shaped or rounded, colorless bodies, which in their appearance are strikingly 

 like small bacteria the they are not bacteria, as they fail to take Giemsa 

 stain. Size of sporulating trophozoites 100 to llO^t by 25/i. Disporous. 



Spore: Shell- valves greatly elongated, tapering gradually toward the 

 ends. Long, attenuated ends of valves hollow and so fragile that it is 

 almost impossible to find an example in which they are not more or less 

 distorted. Sutural plane perpendicular or only slightly oblique to the 

 longest diameter. Polar capsules are spherical and large; slightly conver- 

 gent, opening some distance apart on the anterior side. Coiled polar 

 filament distinct. Sporoplasm confined to large, central part of spores, 

 but extending farther into one valve than the other. Dimensions: total 

 breadth 115 to 140^, sutural diameter about 12/x, diameter of polar capsules 

 6//, length of polar filament 75/i. 



CERATOMYXA TAENIA Davis 



[Figs. 52 and 53] 

 1917 Ceratomyxa taenia Davis 1917 : 224-225 



Habitat: Gall-bladder of Scoliodon terrae-novae; Beaufort. 



Vegetative form: Similar to those of C. sphairophora Davis, and no 

 character has been found by which they may be distinguished. Sporulating 

 trophozoites can be easily distinguished on account of the very different 

 appearance of the spore and their different arrangement within the tropho- 

 zoites. The spores of this species are situated, as is usually the case in 

 Ceratomyxa, with the greater part of the spore parallel to the long axis of 

 the trophozoite, only a part of one valve being bent back along the rest 

 of the spore. Size: sporulating trophozoites length 80ju, breadth 25ju. 

 Disporous. 



Spore: Valves greatly elongated. Shell very thin, the membrance on 

 opposite sides of each valve being in contact for about two-thirds of its 

 length, forming a thin ribbonlike structure; basal third of each valve only 

 slightly compressed; terminal ribbonlike portion of each valve usually 

 twisted so that plane of ribbon is at right angles to the main part of the 

 spore. Polar capsules small, pyriform to spherical and convergent. Coiled 

 polar filament indistinct. Sutural plane perpendicular to the longest 



