CHAPTER XX 



DIPLOZOA AND OCTOMITID/E 



Preliminary — Diplozoa — -Octomitidae — Octomitus — Giardia — References. 



PRELIMINARY. 



We now return to the classification of the Protomonadina given 

 on p. 332, where the order is divided into two suborders, Monozoa 

 and Diplozoa. The Monozoa we have just considered, and in the 

 present chapter the Diplozoa are described. 



SUBORDER 2. DIPLOZOA Hartmann and Chagas, 1911. 

 Definition. — Protomonadina with more or less tendency to bilateral 

 symmetry in undividing forms, as shown by the arrangement of the 

 flagella, by the duplication of the axostyle, with sometimes the 

 nucleus and more rarely of the cytostome. An undulating mem- 

 brane is absent. 



^^Classification. — This suborder may be divided into two families, 

 of which one is of importance in tropical medicine. 



K. Cytostome single or absant; flagella eight in number-- 



Family I, Octomitidce Minchin, 1912. 

 B. Cytostome double; flagella variable in number — Family 2, 



DistomatidcB Senn, 1900. 



Only the first of these families concerns us. 



FAMILY I. OCTOMITID.E Minchin, 1912. 

 Definition. — Diplozoa with eight flagella and with or without a 

 cytostome. 



Type Genus. — Octomitus Prowazek, 1904. 



Classification.— The family is divisible into several genera as 

 follows : — ■ 



A. Anteriorly three pairs and posteriorly one pair of flagella; 



nucleus single, bilaterally lobed or doubled; sucker 

 absent. 

 I. Parasitic — Octomitus. 

 II. Free living — Hexamita. 



B. Antero-laterally one pair, mesially two pairs, and posteriorly 



one pair of flagella ; nucleus usually double ; sucker present 

 — Giardia, 



Octomitus and Giardia concern us; Hexamita does not. 



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