32 FRESH- WATER RHIZOPODS OF NORTH AMERICA. 



Rhizopod. It was discovered by Rosel, and described in a work entitled 

 "Insecten Belustigung ", or Recreation among Insects, published in Nurn- 

 berg in 1755. Rosel calls the animal the little Proteus, and accompanies 

 his description with nineteen well-executed and colored figures engraved 

 by himself. 



Linnaeus, in the Systema Naturae, referring to Rosel's animal, named 

 it Volvox Chaos, and subsequently Chaos Protheus. Pallas called it Volvox 

 Proteus. Miiller afterwards named it Volvox Sphceruta, but later, after having 

 himself observed the animal, described and figured it under the name of 

 Proteus diffluens. 



As the generic name of Proteus had been previously appropriated for 

 the well-known Salamandroid of Adelsberg, Bory de St. Vincent substituted 

 that of Amiba for the animal of Rosel and Miiller, calling it by the various 

 names of Amiba divergens, A. Bcesili, and A. Mulleri. 



Ehrenberg, in the Transactions of the Academ};- of Sciences of Berlin 

 for 1830, indicated and figured a comparatively small Amoeba, the ^th of a 

 line (pp. 39, 75, pi. I, figs. 5), under the name of Amoeba diffluens, regarding 

 it as the same as the Proteus diffluens of Miiller. 



In the Transactions of the following 3-ear, Ehrenberg described what 

 he considered to be a new species with the name of Amoeba princeps. The 

 characters given of this are as follows : Diameter ith of a line; body trans- 

 parent, yellowish, with many easily and voluntarily movable blunt pro- 

 cesses; four times larger than the Proteus. 



This description is accompanied with one of Amoeba diffluens {Proteus 

 diffluens, Miiller), as follows: Diameter ith of a line; body transparent as 

 water, mostly with only three or four variable processes; four times smaller 

 than the preceding species. 



In his great work, the Infusionsthierchen, 1838, Ehrenberg described 

 Amoeba princeps as '"large, yellowish, equalling Jth of a line, provided with 

 a variable number of cylindrical appendages, thick and rounded at the end." 

 The accompanying figures (Taf. VIII, Fig. X) accord with the description, 

 and agree with the familiar common large Amoeba. 



In the same work, Amoeba diffluens is described as " rarely surpassing 

 the ,^th of a line, hyaline; processes variable, moderately long and robust 

 and subacute." Under this species, Ehrenberg places as synonyms the 



