284 FRESH- WATER RHIZOPODS OF NORTH AMERICA. 



describes a form with the name of Gymnoplirys cometa, * which resembles 

 Biomyxa, as represented in fig. 12, pi. XLVII, and figs 7-9, 13, 14, pi. 

 XLVIII. The former, however, differs in having no contractile vesicles. 

 In this respect, likewise, Biomyxa differs from the nearly related Leptophrys 

 of Hertwig and Lesser.f 



As represented in fig. 6, pi. XLVIII, Biomyxa closely resembles the 

 Amceba porrecta of Schultze, \ from the Adriatic 



One of the earliest observed specimens of Biomyxa vagans, represented 

 in fig. 1, pi. XLVIII, occupied, as first seen, a nearly semicircular space, 

 about 0.6 mm. by 0.4 mm. The main protoplasmic mass extended from a 

 common base in three bands, of which the intermediate one was longest 

 and tapering as it was resolved into divergent pseudopodal branches; while 

 the lateral bands expanded outwardly, and presented large circular holes 

 previous to branching. The pseudopodal extensions freely anastomosed 

 with one another. Small contractile vesicles appeared in many places, both 

 in the principal bands and in the pseudopods. The median band and base 

 contained numerous minute fusiform desmids, all of the same kind. 



The protoplasm of the main bands exhibited a faintly striate appear- 

 ance, perhaps due to an arrangement of granules occasioned by currents. 

 Circulation was observed in different directions at the same time, as indi- 

 cated by the arrows in the figure. 



The organism gradually changed its shape, becoming a single baud, 

 then a central elliptical disk, etc. Large angular spaces included in the 

 anastomosis of the pseudopodal extensions would slowly diminish, assume a 

 circular form, and continue to decrease until they seemed to be vacuoles, or 

 in their final closure as if they were contractile vesicles. The pseudopodal 

 filaments were rather quickly projected, and sometimes as quickly con- 

 tracted and entirely withdrawn. Occasionally they would appear tortuous, 

 or would be seen with a slow, waving, or feeble, lashing movement. 



Circulation, indicated by the motion of the granules, occurred along 

 the course of the pseudopods, often in a reverse direction on the two sides 



* Ibidem, 31. In an excellent compilation of "Recent Contributions to o;ir Knowledge of Fresh- 

 water Rhizopods," published in the. Quarterly Journal of Microscopic Science, 1877, 341), Mr. Archer 

 expresses an opinion in regard to Gymnophrys which accords with an early impression of my own in 

 relation to Biomyxa. He remarks "that the figures of this Sarcodinc remind one not a little of a 

 portion of the mass of a Gromia become isolated and detached by some readily conceivable force, having 

 wandered too far from the headquarters." 



t Ibidem, 57, 1874. 



t Ueber d. Organismus d. Polythalamien, 1854, 8, Taf. vii, Fig. 8. 



