THE GENUS TRACHELOMONAS. 



By G. I. Playfair, Research Scholar of the University of 

 Sydney in Hydrobiology and Plankton. 



(Plates i.-v.; and Text-figs. 1-20.) 



Very little attention has been given to this interesting genus 

 of freshwater flagellates. Senn, in his "Anhang zu den Flagellata" 

 (Engler ikPrantl," Die Natiirlichen Pflanzenfamilien, 1900) gives 

 the number of species as six. Stein, however, in " Die Natur- 

 geschichte der Flagellaten " (Abt. iii., H. i. of his " Organismus 

 der Infusionsthiere," 1878), had already figured 10 species. Half 

 of these date back to Ehrenberg, viz., Tr. volvocina, Tr. cylin- 

 drica, Tr. lagenella, Tr. armata, and Tr. caudata^ th<jugh often 

 under other generic names. 7V. hispida Perty, Tr. acuminata 

 Schmarda, 'Tr. bulla Stein, Tr. rugulosa Stein, and Tr. eurystoma 

 Stein, make up the remainder. Kent, "Manual of the Infusoria," 

 1878, gives descriptions of those mentioned by Stein, but figures 

 of five only. Stokes, " Freshwater Infusoria of the United 

 States " (Journ. Trenton Nat. Hist. Soc, 1888), describes five 

 other species, Tr. verrucosa Stokes, Tr. aca^ithostoma Stokes, Tr. 

 torta Kellicott, Tr. piscatoris (Fisher) Stokes, and Tr. urceolata 

 Stokes, with figures of the last three. In " Notices of New 

 Freshwater Infusoria" (Amer. Phil. Soc, 1890), the same author 

 proposed four other species, viz., Tr. cervicula, Tr. similis, Tr. 

 obovata, Tr. spinosa. Other publications containing notices of 

 new forms are: Klebs, "Organization einiger Flagellatengrupper" 

 (Bot. Inst, zu Tubingen, 1881-85), Tr. reticulata'KlQh^; Dangeard, 

 "Recherchessur les Eugleniens"(Botaniste, 1 902), Tr. intermedia 

 Dangeard, with notes and figures of Tr. volvociiia, Tr. rugulosa^ 

 Tr. lagenella, Tr. hispida, Tr. candata, Tr. armata, and Tr. 

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