344 HANDBOOK OF PROTOZOOLOGY 



Genus CoUinia Cepede. Body ovoid; without cytostome. 

 Cilia are arranged in longitudinal rows. One to several con- 

 tractile vacuoles. Parasites in the coelom of fresh-water Crusta- 

 cea (Gammarus, Neoniphargus, and Asellus.) 



CoUinia circulans (Balbiani) (Fig. 147,/). Polymorphic. In 

 the blood vessel of Asellus aquaticus. 



Genus Protophrya Kofoid. Body ellipsoidal to pyriform. 

 Macronucleus elliptical; a micronucleus; contractile vacuole at 

 the posterior end. One species. 



Protophrya ovicola Kofoid (Fig. 147, g, h). Body about 60 

 microns long. Parasitic in the uterus of the mollusc, Littorina 

 rudis. 



Genus Isselina Cepede. Similar to Protophrya. One species 

 in the mantle cavity of Littorina ohtusata. 



Genus Orchitophrya Cepede. Body pyriform; ciliary rows 

 are curved. Macronucleus spherical. 



Orchitophrya stellarum Cepede (Fig. 147, i). In the gonads 

 of the echinoderm, Asteracanthion (Asterias) rubens. 



Genus Monomastix Roux. Elongated cylindrical; body 

 flattened; ciliation uniform. Pointed anterior end with trichites 

 and a long flagellum. Two macronuclei and micronuclei. Free- 

 living. Saprozoic. 



Monomastix ciliatus Roux (Fig. 147, j). Body about 75 

 microns long by 14 microns broad. In stagnant water. 



Suborder 2 Gymnostomina Butschli 



The Holotrichida placed in this suborder possess a cyto- 

 stome which is closed except at the time of actual food taking. 

 In several genera longer cilia form a peristomal ring; the cyto- 

 stome is, as a rule, terminal. The body form is usually definite, 

 a distinct pellicle being present in all forms, and in some, plate- 

 lets are developed. 



The suborder is divided into four families: 



Thick cortex on various parts of body; peristome narrow and long; 



all parasitic Family 1 Nicollellidae 



No thick cortex 



With terminal cytostome Family 2 Holophryidae 



Cytostome not terminal 



Anterior end with proboscis Family 3 Trachelinidae 



Usually with an oral basket; no proboscis Family 4 Chilodontidae 



