INFUSORIA 51 



Key to the genera of Enchelinidae here described: 



fli Cilia cover whole body. 



&i Body not covered with rectangular plates. 

 Ci Body not elongate and contractile. 

 di Gullet absent or short. 

 Ci Posterior bristle not present. 



/i Mouth terminal ; body ovoid 1. Holophrya 



/, Mouth subterminal ; body with slight neck 2. Enchelys 



^2 Posterior bristle present 3. Urotricha 



^2 Gullet long and lined with a membrane 4. Prorodon 



C2 Body elongate and contractile. 



d^ Body flask-shaped with contractile neck 5. Lacrymaria 



d^ Body very long and contractile 7. Trachelocerca 



62 Body covered with rectangular plates 6. Coleps 



02 Cilia confined to 1 or 2 girdles. 



&i Deep equatorial furrow present 8. Mesodinium 



&2 No such furrow 9. Didinium 



1. Holophrya Ehrenberg. Body striated, cylindrical or ovoid; 

 eiliation uniform ; no trichocysts ; 6 species ; in fresh and salt water. 









Fig. 72 Fig. 73 Fig. 74 



Fig. 72 — Holophrya discolor (from Bronn). Fig. 73 — Enchelys pupa (Conn), 

 llg. 74 — Urotricha fareta (Conn). 



H. discolor Ehr. (Fig. 72). Body ovoid ; length .04 mm. : in standing 

 water. 



2. Enchelys 0. F. Miiller. Anterior end somewhat elongated and 

 truncated with subterminal mouth: 5 species; in fresh and salt water. 



E. pupa Ehrenberg (Fig. 73). Body ovoid; length .08 mm.; color 

 often greenish. 



3. Urotricha Claparede and Lachmann. Like Holophrya, but with 

 a bristle at hinder end: 2 species; in fresh water. 



U. fareta CI. and Each. (Fig. 74). Springs with its bristle; length 

 .02 mm. 



4. Prorodon Ehrenberg. Body ovate or ellipsoid, with a long 

 gullet lined by a membrane: 8 species; in fresh water. 



P. griseus Claparede and Lachmann. Length .25 mm.: in standing 

 water. 



5. Lacrymaria Ehrenberg. Body flask-shaped, with a contractile 

 neck and spiral striations : 4 species ; in fresh and salt water. 



