338 BIOLOGY OF THE PROTOZOA 



the amoeboid phase, sexual processes unknown. The amoeboid 

 phase is represented by small creeping amoebae which have been 

 generally included as Amoeba Umax, and known as "limax" forms. 

 These were separated from the genus Amoeba by Chatton and 

 Lalung-Bonnaire (1912) under the name Vahlkampfia. The forms 

 with a single flagellum in the flagellated stage are retained under the 

 generic name VaMkamyfia although it is by no means assured that 

 all "limax" amoeba? are thus dimorphic. Forms with two flagella 

 are grouped in the genus Ndgleria and forms with three flagella in 

 the genus Trimastigamoeba, Whitmore. Parasitic forms, regarded 

 by Craig (1906) as a cause of human dysentery and with a flagellated 

 phase with one flagellum, are included in the genus Craiqia. Genera 

 recognized: Vahlhampfia, Ch. and L. B., type V. bistadialis 

 Puschkarew (Fig. 42, p. 86); Ndgleria, Alex.; type N. gruberi, and 

 N. 7J7/nda/a,I)angeard (Fig. 12, p. 34); Trimasiigamoeha, Whitmore; 

 type T. phUipiyinensis; Craigia, Calks. ; type C. hominis. 



Family 2. Amoebidae (authors generally: em. Doflein, em. 

 Calkins).— The nsual types of free living amoeba^ are grouped in this 

 family. Flagella, so far as known, are absent at all stages. Nuclei 

 single, double, or multiple; contractile vacuole usually single, 

 present generally in fresh-water forms. Reproduction by simple 

 division in vegetative forms, hy multiple division during quiescent 

 phases. The great majority of forms are aquatic and developmental 

 phases of other types {e. g., mycetozoa) may be easily mistaken for 

 amoebae. Others are semi-terrestrial living in damp earth, moss, 

 etc., where they play a part in keeping down bacteria of the soil 

 (see Goode^•). Sexual processes in no case have been substantiated, 

 but a peculiar process of syngamy has been described by Nagler, 

 Erdmann and others in the case of Amoeba diploidea (see p. 549). 

 Genera: Amoeba, Fhrenberg; PeJomyxa, Greeft'. 



Family 3. Endamoebidse.— These are parasitic amoebae widely 

 distributed throughout the animal kingdom and with character- 

 istic vegetative phases during which the organisms live as harmless 

 commensals, or more rarely, as pathogenic parasites in the host, 

 and with permanent cyst stages hy which infection is carried by 

 means of contaminative infection. The genus generall^' recognized 

 is represented by a vast number of species with ill-defined diagnostic 

 characters (genus: Endamoeba) while other genera (e. g., Endolimaxf 

 Covncilmania, etc.) are forms about which the taxonomic position is 

 still in dispute. Nutrition is either holozoic, saprozoic or heterozoic. 



Family 4. Paramcebidae.— Forms with single nucleus and pecu- 

 liar cytoplasmic structure (Nebenkern) variousl}^ interpreted as a 

 kinetic element, intracellular parasite, etc. Both free-living and 

 parasitic species. Genus: Paramoeba. 



