OF THE ARCELLINA. 551 



animalcules from beiug diied up during the alternations of diyness mth 

 moisture they are exposed to by their habitat in mosses. They are procured 

 by lightly pressing the Jungennanniae, moistened by the rains of November 

 or December, or after they have been j^reserved a little time in water. 



This, as Dujardin remarks, is evidently a new genus, intermediate be- 

 tween the naked and the loricated Ehizopoda, and standing in a certain 

 relation with the NoctUucce. {A. S. N., 1852, vol. xviii. p. 240.) 



No species named. 



Genus PAMPHAGUS (Bailey). — An Amoebifoi-m being, covered by a deli- 

 cate elastic integument, which, although it presents astonishing changes of 

 form, and offers a certain amount of resistance to internal and external pres- 

 sui'e, yet admits of the animalcule transfixing itself upon any denser thin 

 portion of matter without any apparent damage (p. 220). 



They connect, says their discoverer, " the genus Amceba with Difftugia, 

 agreeing with the first in the soft body without shell, but differing in having 

 tme feelers or rhizopods confined to the anterior part of the body," or to the 

 region of the mouth, as in Diffiugia. A specimen of PampliaguSy we may 

 remark, is equivalent to a Difftugia "^dthout a true shell and with no ex- 

 traneous matters to thicken and strengthen its covering. Dr. Bailey met 

 with these animalcules in a vivarium, into which " bits of boiled beans and 

 potatoes had occasionally been introduced as food for other animalcules," 

 and numerous starch granules were found in their interior. He also repre- 

 sents it as having a mouth, and, being an adherent of Ehrenberg, as polygas- 

 tric ; but the mouth so described was the orifice of the sac through which 

 the pseudopodes were protruded, and therefore the homologue of the foramen 

 of monothalamous shells. 



This genus is evidently very closely allied to Corycia (Duj.). The only 

 difference of moment is that in the latter the expansions of the sac proceed 

 fi'om any part of the surface, whilst in Pampliagus its discoverer describes 

 them as given off only from one spot at the anterior end. 



FAMILY II.— ARCELLINA (Ehr.) (Pt. I. p. 201 et seq.) 

 (XXI. 6-17.) 



Amoehce invested with a single-chambered eeU or lorica, having also but 

 one opening, mouth, or foramen. The animal substance or sarcode contained 

 within the sheU is indistinguishable from that of the naked Amcehce, and is 

 not more organized. The form of the pseudopodes given off from around the 

 mouth of the shell are to some extent employed in defining species ; but the 

 size and confonnation of the shell and of its opening are of much more im- 

 portance systematically. 



Ehrenberg instituted this family for all one -chambered Phizopodous sheUs 

 which, in his belief, were of a siHcious composition, and rejected from it 

 some similar sheUs which were of a calcareous character. This distinction, 

 however, is based on erroneous notions (p. 219) ; and naturalists now concur 

 m bringing together all unilocular Phizopoda into one group, under the name 

 of Monothalamia. 



The Arcellina were represented by Ehrenberg as poly gastric animals, 

 with^ an ahmentary canal, and enclosed by a lorica, through the single 

 openmg of which they extended their variable processes. He also described 

 digestive sacs, but was unable to discover either theii- mode of reproduction 

 or their multiplication by fission or gemmae. 



Only four genera of Arcellina were enumerated by Ehrenberg; their cha- 

 racters and mutual relations are shown in the following tabular view : — 



