GENUS PAMPHAGUS— PAMPHAGUS MUTABILIS. 193 



ceded only by the vernacular one of ' Corycie,' and not until several years 

 later was that of Corycia employed. 



Pamphag^us mntabilis is a remarkable creature, comparable to an 

 Amcfiba in which the ectosarc had become coagulated, and retained its 

 elasticity, but lost its voluntary power of extension. The investing mem- 

 brane or shell is so thin, transparent, and elastic, and yet so intimately 

 adherent or continuous with the interior fluent sarcode, that it appears 

 scarcely more differentiated than the limiting ectosarc in Amoeba verrucosa. 



The animal is commonly of a compressed oval or ovate form (figs. 1, 3, 5, 

 7, 8, 9, pi. XXXIII), and in transverse section lenticular (figs. 2, 6). The 

 fundus is mostly more or less acute, and sometimes acuminate, but is also in 

 a variable degree obtusely roxxnded. The lateral borders are acute, extend- 

 ing to the fundus. The oral pole is usually the narrower ; and the mouth 

 is terminal, small, transversely oval, and bounded by a thickened border. 

 At times this has appeared continuous ; at others, interrupted on one side, 

 as represented in fig. 3. Above the mouth, at a variable distance, the 

 membrane often exhibits a circular line, apparently due to a temporary 

 folding, as seen in figs. 7-9. The animal moves slowly in an upright posi- 

 tion, with the mouth downward, and the delicate, long, filamentous pseudo- 

 pods radiating in any and all directions, but mostly on a plane at right 

 angles to the mouth. In movement the body of the animal is sometimes 

 bent, curved, or twisted, and the investing membrane becomes variously 

 inflected and wrinkled. The pseudopods usually diverge in straight lines, 

 acutely branching, and often extend to a length even gi'eater than that of 

 the body. The angles of the forked branches often appear webbed from 

 expansions of the protoplasm ; and the terminal branches become more and 

 more delicate. Occasionally the pseudopods assume a tortuous appearance, 

 as seen in figs. 1, 2, and sometimes one or more are seen suddenly and 

 abruptly to bend in a geniculate manner, as seen in figs. 5, 7. When the 

 pseudopods are entirely withdrawn, the animal falls, and lies upon one of its 

 broader sides, as usual with most of the shell-covered protoplasts of com- 

 pressed form. 



The interior sarcode of Famphagus mutabilis always completely fills 

 and is continuous with the deHcate investing integument, never leaving any 

 vacant space, such as is frequently observed in Euglypha and most shell- 



13 RHIZ 



