52 



PROTOZOA 



Fig. 75 



Lacrvmaria nlor 

 (Conn). 



Fig. 76 



Coleps hirtus 

 (Conn). 



L. olor (0. F. Miiller) (Fig. 75). Body extremely 

 elastic, colorless or gi'een; length without neck .2 mm.; 

 neck may be much longer than body: in fresh water. 



L. lagenula Claparede and Lachmann. Body flask- 

 shaped, with a short conical neck which has a crown 

 of longer cilia; length up to .16 mm.: in decaying 

 marine and fresh-water algae. 



6. Coleps Nitzsch. Barrel-shaped, \ , . 

 rigid, with an armor composed of rect- 

 angular plates between which the cilia 

 })roject: 3 species; in fresh water. 



C. hirtus Ehrenberg (Fig. 76). Gray 

 or green; length .04 mm.: in swamps. 



7. Trachelocerca Ehrenberg. Body 

 very long, slender, and contractile: ma- 

 rine; 1 species. 



T. phcEnicopterus Cohn (Fig. 77). 

 Length up to 1.7 mm.; with a four-sided mouth, which may not be 

 seen : Woods Hole. 



8. Mesodiniitm Stein. Body globular or conical, with a deep furrow 

 around the middle from which spring one or more rows of cirri; 4 con- 

 tractile tentacles in the mouth : 3 species ; in fresh and salt 

 water. 



M. cinctum Calkins (Fig. 78). Cirri projecting forward 

 number about 30: marine; Woods Hole. 



9. DiDlNiUM Stein. Body cylindrical, with 1 or 2 

 girdles of cilia and with a horseshoe-shaped macronucleus ; 

 fonvard end a projecting cone with the mouth at the tip: 

 2 species; in fresh water. 



D. nasutum* (0. F. Mlillei) (Fig. 79). Length. 1 mm.: 

 feeds on Paramecium and 

 other large infusorians. 



Family 2. 



TRACHELINIDAE. 



Dorsal side of body 



aiched; mouth terminal 



or subterminal, usually 



lon<i' 



Fig. 77 

 phanicop' ^t the end ot a 

 (Calkins), neck: 6 genera. 



Fig. 79 



Fig. 78 — Mcsodinium cinctum 

 (CaUcins). Fig. 79 — Didinium 

 nasutum (Mast). 



* See "The Reactions of DiUiuium nasutum," etc., by S, O, Mast, Biol. Bull. 

 Vol. 16, p. 91, 1909. 



