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218 ORDER TRYPANOSOMATA.spores commonly follows upon the simple encystment of a single animalcule. Therecognition of these important reproductive phenomena is chiefly due to the recentpainstaking investigations of Messrs. Dallinger and Drysdale, whose researches inlocomotive and supplementary appendages, the classthis direction are fully recorded in the descriptive accounts given of MonasDallingerii, Cercomonas typica, Tetramitus rostrata, Dallingeria Drysdali, and severalspecies of Heteromtta.With reference to the variously modified characters of the oral system, and of thebe convenientlysubdivided into primary sections or Orders as below :of the Flagellata mayORDER I.TRYPANOSOMATA.A.Ingestive area diffuse.B.Ingestive area discoidal,limited to the anteriorregion ;no true mouth.C.Ingestive areaconstituting a true anddistinct mouth.Flagellum supplemented byllobate pseudopodia . . . /.Flagellum supplemented by). .ray-like pseudopodia JFlagella representing the sole)organs of locomotion . . /Flagellum rudimentary, supplementedby an undulatingmembrane .. ..Flagellum issuing from thecentre of a collar-like extensilemembraneFlagellum not supplemented)by cilia /Flagellum supplemented bya more or less highly developedciliary systemII.III.IV.RHIZO-FLAGELLATA.RADIO-FLAGELLATA.FLAGELLATA-PANTOSTOMATA.V. CHOANO-FLAGELLATA.VI. FLAGELLATA-EUSTOMATA.VII. CILIO-FLAGELLATA.Order I. TRYPANOSOMATA, S. K.Animalcules flattened or lamellate, one or more of the lateral bordersforming a frill-like undulating membrane by the vibrations of whichprogress is effected one; extremity sometimes attenuate and somewhatresembling a flagellum. Oral or ingestive area undefined.Two species only, representing but a single genus, can be as yet referred tothis newly established order. So far as it can be at present determined, these twoendoparasitic types would seem to lie at the base of all the succeeding more typicalsections of the Infusoria Flagellata and Ciliata. Although no positive flagellum ispresent, the growth of such an organ is evidently foreshadowed in the slender taglikeappendage of Trypanosoma sanguinis, while, on the other hand, the undulatingmembranous border, constituting the essential organ of locomotion, may withouthesitation be regarded as closely, if not absolutely, homologous with the similarundulating frill-like border present in the earlier developmental phases of Sttntor,Euplotes, and other higher Ciliate types, and which eventually splits up to form thecharacteristic adoral fringe.GENUS I.TRYPANOSOMA, Gruby.F" Animalcules free-swimming, compressed ;one side produced as a thin,undulating, frill-like border the anterior ;extremity sometimes produced asa long tag-like or flagellate appendage. No distinct oral aperture.Occurring in the blood of Amphibia, and within the intestinal viscera ofdomestic poultry.