GENUS MASTIGAMCEBA . 221 



The some half a dozen species as yet known that may be consistently referred 

 to this order, intimately connect with each other the two classes of the' Rhizopoda, 

 as represented by the Amoebina, and the typical Infusoria-Flagellata. In accordance 

 with the number and character of their flagelliform and pseudopodic appendages 

 they admit of the following generic grouping : 



GENERA OF RHIZO-FLAGELLATA. 



Flagellum single, / Re P ent 

 anteriorly situated. 



Sedentary, with radiating digitiform prolongations .. ,, 3. Rhizomonas. 

 Flagella multiple, inconstant in number and position , , 4. Podostoma. 



GENUS I. MASTIGAMCEBA, Schulze. 



Animalcules repent, amoeba-like, changeable in form, emitting pseudo- 

 podia from all parts of the periphery, the anterior extremity bearing a single, 

 long, non-retractile, lash-like flagellum. 



Mastigamceba aspera, Schulze. PL. I. FIG. 21. 



Body when extended oval, depressed, pointed anteriorly ; pseudopodia 

 cylindrical, unbranched, digitiform, diverging in somewhat regular order 

 from the lateral margins of the periphery, those at the posterior extremity 

 of the body shorter than the others, emitting extremely fine ray-like sar- 

 codic projections, similar to those of A mceba (Pelomyxd) villosa ; flagellum 

 issuing from the pointed anterior extremity, about equal in length to the 

 body ; entire external surface, including more especially the pseudopodia, 

 beset with exceedingly minute refringent rod-like structures which commu- 

 nicate to it a hispid aspect. Contractile vesicles two in number, situated 

 near the posterior extremity. A subspheroidal endoplast-like structure 

 developed anteriorly ; endoplasm enclosing numerous reddish - yellow 

 spherules and colourless granules. Length of body 1-150". 



HAB. Pond water. 



Excepting for its smaller size and the presence of the anteriorly developed 

 flagellum, the representatives of this species correspond in a remarkable manner 

 with the Dinamceba mirabilis of Dr. Joseph Leidy, as recently figured in his magni- 

 ficent monograph of the Freshwater Rhizopods of North America. 



Mastigamceba simplex, S. K. PL. I. FIG. 30. 



Body when extended usually widest and rounded at the anterior extre- 

 mity, tapering posteriorly ; pseudopodia irregular in shape, simple, lobate, 

 or furcately branched, not differentiated from one another as in M. aspera, 

 usually directed backwards ; flagellum antero-terminal, about twice the 

 length of the body ; external surface entirely smooth ; contractile vesicle 



