FLAGELLATE PROTOZOA (MASTIGOPHORA) 247 



28 (27) Free, like Monas, but with the anterior end oblique. 



Physomonas Kent. 

 Representative species Physomonas elongata Stokes 1886. 



Body elongate-ovate, changeable in shape; free-swimming or temporarily 

 attached by a very short pedicel. Flagella two, unequal. Contractile 

 vacuole anterior in position. Length about 1 2 /* Swamp water. 



FIG. 374. Physomonas elongata. cv, contractile vacuole; n, nucleus. 

 X 1000. (After Stokes.) 



29 (22) Forming colonies. Two flagella 30 



3 (33) One zooid upon the end of each branch ; ...... 31 



31 (32) Pedicel rigid Dendromonas Stein. 



Representative species Dendromonas virgaria Weisse 1845. 



Body of zooid pyriform, compressed, with an anterior, 

 lip-like projection from the base of which arise the two 

 unequal flagella. Nucleus single; contractile vacuole one 

 or two. Colony branching dichotomously. A colony may 

 include over one hundred zooids. Length of zooid 8 to 10 AC. 

 Pond water. 



FIG. 375. Dendromonas virgaria. Colony X 160; single zooid X 93 5 . 

 (After Blochmann.) 



32 (31) Pedicel flexible Ramosonema Kent. 



Representative species Ramosonema laxum Kent 1871. 



Zooids pyriform, compressed, obliquely truncate anteriorly. Pedicel 

 very slender, threadlike. A colony may include as many as twenty or 

 more zooids. Length of zooids 8 p. Pond water. 



FIG. 376. Ramosonema laxum. cv, contractile vacuole; , nucleus. Colony X 350; 

 single zooid X 1000. (After Kent.) 



33 (30) Many zooids upon each branch 34 



34 (35) Stalk short, branching dichotomously once or twice. 



Cephalothamnium Stein. 

 Representative species. . , Cephalothamnium caespitosum Kent 1880. 



Zooids irregularly pyriform, in clusters of two or three 

 or as many as six or eight on the summit of a simple or 

 slightly branched pedicel. Pedicel very short. Length 

 of zooid about 6 n. Fresh water, attached to Cyclops. 



FIG. 377. Cephalothamnium caespitosum. X 875. (After Conn.) 



