1 68 THE MASTIGOPHORA 



Pleuromonas, Perty ; Phyllomitus, Stein ; Colponema, Stein ; Rhynchomonas, 

 Klebs ; Oxyrrhis (Fig. 10 (2)), Duj. marine. Bodo can execute character- 

 istic jumping movements by means of the gubernaculum. It captures 

 its food (bacteria and infusoria) and sucks out the protoplasmic contents 

 by means of a rostral process (rostral ingestion). According to Dallinger 

 and Drysdale a process of plasmodium- formation occurs in this genii?, 

 followed by encystment and subsequent division of the protoplasmic 

 contents into numerous swarm-spores (Fig. 5 (23-26)). In Oxyrrhis there 

 is a large oral funnel and a rudimentary pharynx similar to that of the 

 Euglenoidea. This genus is said to divide transversely instead of 

 longitudinally as in all other Heteromastigoda. The genus Costia 

 (Leclerq) with three flagella, reposing in a groove when at rest, may 

 belong to this sub-tribe (see p. 157). B. Sedentary and usually colonial 

 forms, protected by a cup-shaped or closed theca and attached to the 

 base of it by the gubernaculum. At the anterior extremity there is a 

 plate-like expansion of the ectoplasm (the peristome). (Bikoecina, Stein) ; 

 Bicosoeca, Clark, solitary or in rosettes ; (B. socialis, Lauterborn). 

 Peristome thin and membranous. Freshwater and marine. Poterio- 

 dendron, Stein, fixed, " dinobryoid " association of stalked thecate 

 individuals ; peristome thick, proboscis-like. 



The Bikoecina appear to suggest a transition from the Lissoflagellata 

 to the Choanoflagellata in virtue of their peristome, which is perhaps 

 comparable to the collar. 



The Family TRYPANOSOMATIDAE, containing the blood-parasites Try- 

 panophis, Trypanoplasma, and Trypanosoma, belong to this sub-tribe. 

 The family is fully described in Section G, p. 193. 



SUB-TRIBE 4. ISOMASTIGODA. Monaxonic body with two equal 

 flagella at the anterior end. A. Solitary (Amphimonadina). Amphimonas, 

 Duj. ; Streptomonas, Klebs ; Diplomita, Kent. Freshwater. B. Colonial 

 (Spongomonadina). Numerous individuals united "in a common jelly 

 or in branched gelatinous tubes, the end of each of which is inhabited by 

 a single and distinct individual." l Spongomonas, Stein ; Cladomonas, 

 Stein ; Rhipidodendron, Stein. Diplomita (Kent) is now regarded as an 

 individual of Spongomonas living isolated in the theca of a Bicosoeca. All 

 freshwater. 



An interesting Protozoon which is known by the name of 

 Pseudospora volvocis, Cienkowski, and was placed by Biitschli in the 

 tribe Isomastigoda, is found parasitic upon Volwx. According to 

 Robertson (18), it has three forms, each from 12 to 30 /x in diameter. 

 A, an amoeboid form ; B, a pear-shaped flagellate form, with two 

 flagella at one end ; C, a spherical Actinophrys-like form. In each of 

 these forms there is a single definite nucleus containing a centrally 

 placed karyosome surrounded by clear nucleoplasm. The amoeboid 

 form feeds by ingesting individuals of the Volwx colony, and it 

 gives rise to the flagellate form, which swims away and attacks 

 another colony. Reproduction of the amoeboid form occurs 



1 Lankester, E. R., Enci/. Brit., 9th Ed., Art. "Protozoa." 



