A VARIETY OF AN1SONEMA VITREA. 



BY C. H. EDMONDSON. 



Anisonema ritrca (Dujardin) is a flagellated protozoan, elongate-oval in 

 form, the anterior end broadly rounded, the posterior more acutely rounded. 

 An oral groove is present on the ventral surface, and near the anterior end 

 of this groove are inserted two flagella of unequal length. The longer and 

 stouter of the two flagella is curved backwards, being non-vibratile, trail- 

 ing along behind as the animal advances. The shorter flagellum is directed 

 forward, its vibrations causing the oscillating movement of the organism. 

 A contractile vacuole is present, as is also a spherical nucleus, the latter 

 being central in position. 



Anisonema vitrea is distinguished from other species of the genus by 

 eight furrowed surfaces extending in a slightly spiral manner from one end 

 of the body to the other. This species is a salt-water form and has been 

 observed at Woods Hole by Calkins. 



During the summer of 1906, while working on marine Protozoa at the 

 Tortugas, Fla., I made a careful study of a form which, no doubt, should 

 be considered as a variety of the above species and which I would entitle 

 Anisonema vitrea (Duj.) var. pentagona. 



The body of this variety is somewhat shorter and thicker than the 

 species reported from Woods Hole, the Tortugas form measuring 40 ^ in 

 length by 30^ in width. The chief distinction, however, between the species 

 and the variety is that the latter possesses but five longitudinal furrows 

 which are well marked and very deep. In other respects the variety re- 

 sembles the species. 



The eight-furrowed form was not observed at the Tortugas, but the 

 pentagonal variety was one of the most common species, being found abun- 

 dantly within the moat surrounding Fort Jefferson and also in infusions 

 of gulf-weed. 



Reproduction of the organism takes place by longitudinal division. 



Figs, i and 2 represent lateral and transverse views, respectively. 



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