INFUSORIA 



61 



Key to the families of Hypotrichida here described: 



! Body usually elongate and broad, with ventral cilia 1. OXYTRICHIDAE 



o a Body more or less circular with very long bristles and cilia usually absent. 



2. EUPLOTIDAE 



FAMILY 1. OXYTEICHIDAE. 



Body somewhat elongate with arched dorsal and flat ventral side, 

 the latter with cilia, bristles, etc.; mouth near the middle with an oral 

 groove running backwards : 21 genera ; in fresh and salt water. 



Key to the genera of Oxytrichidae here described: 



! Several median longitudinal rows of continuous cilia. 

 & x Five or more rows of cilia. 



c x Mostly fresh-water animals 1. UBOSTYLA 



c 2 Marine animals 2. EPICLINTES 



& 2 Less than 5 rows of cilia. 



G! Neither anterior nor anal bristles ; body acute anteriorly . . 3. STICHOTRICHA 

 c 2 Such bristles present ; body usually broad. 



d^ Animals mostly marine 4. AMPHIBIA 



d 2 Animals mostly in fresh water. 

 1 Two median rows of cilia. 



/! Three anterior and no anal bristles 5. UBOLEPTUS 



f 2 No anterior bristles ; anal bristles present 7. HOLOSTICHA 



e 2 Three or 4 rows, body broad and rectangular. 6. ONYCHODROMUS 



C 2 No median rows of continuous cilia ; but marginal rows present. 



61 No caudal bristles 8. OXYTBICHA 



6 2 Three long caudal bristles 9. STYLONYCHIA 



1. UROSTYLA Ehrenberg. Body flexible, elliptical, 

 with longitudinal striations and rows of cilia; oral 

 groove at forward end; 5 to 12 long anal bristles in 

 an oblique row, and 3 or more anterior bristles: 6 

 species; in fresh and salt water. 



U. trichota (Stokes) (Fig. 106). Length .3 mm.; 

 5 anal and about 20 anterior bristles: in fresh water. 



2. EPICLINTES Stein. Body flexible, elongate, the 

 forward half being ovate, the hinder end slender and 

 cylindrical; several longitudinal rows of cilia: 1 

 species; marine. 



E. radiosa Quenner- 

 stedt (Fig. 107). Length 



.045 mm.; 5 large bristles at Fig. wiEpidintes radiosa 



(Calkins). 



Pig. 106 



Urostyla trichota 

 (Conn). 



forward end: Woods Hole. 



3. STICHOTRICHA Perty. Body cylindrical and very contractile, 

 with acute forward end; oral groove extending back to middle of 

 body; 2 or 3 rows of cilia; color often green: 4 species; in fresh and 

 salt water. 



S. secunda Perty (Fig. 108). Length .2 mm.: in fresh water. 



