418 PROTOZOOLOGY 



Subclass 1 Rhizopoda Siebold 



The name Rhizopoda has often been used to designate the entire 

 class, but it is used here for one of the subclasses, which is further 

 subdivided into five orders, as follows: 



Without test or shell 



With radiating pseudopodia Order 1 Proteomyxa 



With rhizopodia; forming Plasmodium. . .Order 2 Mycetozoa (p. 427) 

 With lobopodia Order 3 Amoebina (p. 435) 



With test or shell 



Test single-chambered; chitinous Order 4 Testacea (p. 472) 



Test 1- to many-chambered; calcareous . . Order 5 Foraminifera (p. 493) 



Order 1 Proteomyxa Lankester 



A number of incompletely known Rhizopods are placed in this 

 group. The pseudopodia are filopodia which often branch or anas- 

 tomose with one another. In this respect the Proteomyxa show 

 affinity to the Mycetozoa. Flagellate swarmers and encystment occur 

 commonly. The majority of Proteomyxa lead parasitic life in algae 

 or higher plants in fresh or salt water. Taxonomy (Valkanov, 1940). 



Pseudoplasmodium-formation Family 1 Labyrinthulidae 



Solitary and Heliozoa-like 



With flagellate swarmers Family 2 Pseudosporidae (p. 420) 



Without flagellate swarmers Family 3 Vampyrellidae (p. 420) 



Family 1 Labyrinthulidae Haeckel 



Small fusiform protoplasmic masses are grouped in network of 

 sparingly branched and anastomosing filopodia; individuals encyst 

 independently; with or without flagellate stages. 



Genus Labyrinthula Cienkowski. Minute forms feeding on various 

 species of algae in fresh or salt water; often brightly colored due to 

 carotin. Jepps (1931) found these organisms common in marine 

 aquaria. Young (1943) considers the six known species as actually 

 three species and two varieties, while Watson (1951) holds that only 

 one species, L. macrocystis, should be recognized. 



L. cienkowskii Zopf (Fig. 176, a). Attacks Vaucheria in fresh water. 



L. macrocystis Cienkowski. Renn (1934, 1936) found a species in 

 the diseased leaf-tissue of the 'spotting and darkening' eel-grass, 

 Zostera marina, along the Atlantic coast of the United States. Young 

 (1943) identified the organism which he studied as L. macrocystis, 

 and noted that its hosts included various algae and three genera of 

 Naiadaceae: Zostera, Ruppia and Zannichellia. 



The 'net-plasmodium' contains fusiform cells which average in size 



