252 ORDER FLAGELLATA-PANTOSTOMATA. 



to the genus Spumella of Cienkowski. The absence, however, of the two shorter 

 flagella at once demonstrates the necessity of their generic separation. 



It is in connection with this form that Professor James-Clark has sought to demon- 

 strate the existence of a distinct mouth, which, in consequence of his having witnessed 

 the entrance of food at this spot on many occasions, he maintained to be situated 

 between the base of the flagellum and the lip-like prominence. O. Biitschli again has 

 more recently advocated the recognition of the lip-like prominence as the recipient 

 of the food-substances that are thrown backwards against the body by the vibratile 

 action of the flagellum. On repeated occasions, however, the author has satisfied 

 himself that the ingestive area has no such restricted limits, but that it is distributed 

 throughout the entire peripheral surface, from any point of which, if a food-particle 

 strikes it, a film of sarcode flows out to seize it. It is at the same time requisite to 

 observe that in the majority of instances these particles are thrown back with such 

 precision as to fall upon the lip-like prominence or other portion of the anterior 

 border, a prolonged observation of the same animalcule being usually requisite for 

 the detection of those more exceptional instances in which it impinges upon, and is 

 engulphed by, the lateral or posterior region. The contractile vesicle and endoplast 

 in this species, in accordance with Biitschli's observations, lay close by side of 

 one another towards the anterior border of the body. Professor James-Clark, 

 however, gives a more posterior location to the last-named structure, a similar posi- 

 tion being distinctive of the examples observed and here figured by the author. 

 When swimming, this species glides along smoothly in a straightforward direction, 

 propelled by the whirling motion of the distal extremity of the flagellum, which 

 otherwise presents that rigid arcuate aspect which characterizes the fixed condi- 

 tion ; the body varies to no appreciable extent in this locomotive form from the 

 more typical sedentary phase. The Monas neglecta of James-Clark, separated 

 from M. (Oikomonas) termo by that authority on account of the more active pulsation 

 and slightly more anterior location of the contractile vesicle, and by the greater length 

 and more sigmoid flexure of the anterior flagellum, but agreeing in all other essential 

 details with the present species, while referable to the genus Oikomonas, appears 

 to possess almost too slender a claim for independent specific recognition. 



Oikomonas obliquus, S. K. PL. XIII. FIG. 72. 



Body subspherical, rounded posteriorly, with a strongly developed 

 conical anterior lip-like prominence; flagellum about three times the length 

 of the body, projecting from the notch produced by the abrupt rising of the 

 anterior lip, rigid and slightly arcuate, deflected at an angle of about 45 

 from the perpendicular axis of the body ; pedicle slender, about equal to 

 the body in length ; parenchyma very clear and transparent. Greatest 

 length 1-7500". HAB. Pond water. 



Although somewhat resembling Oikomonas termo, this species may be readily 

 distinguishable from that form by its exceedingly minute size and the remarkably 

 oblique flexure of the flagellum. This organ in both the latter and preceding 

 type is continuous at its base with the axial line of the body, but becomes slightly 

 curved in the distal portion of its course ; here, however, we find it bent aside 

 from its point of origin at an angle of no less than forty-five degrees. In connec- 

 tion with this species a remarkable phenomenon was observed relating to the 

 inceptive capacities and subsequent method of getting rid of effete and unassi- 

 milated food-particles. Finely pulverized carmine was voraciously swallowed by 

 the monads, and in many instances in such a quantity that the entire parenchyma 

 became filled with small spherical aggregations of this pigment, leaving no space for 

 further importations. It was now determined to ascertain in what manner the 

 indigestible portions would be disposed of; this after a little patient waiting was 

 fully revealed. Piece by piece these effete rejectamenta were released from the 



