ECTOPARASITIC PROTOZOA 17 



Dr. Entz, with the result that we are in complete agreement as to 

 the identity of the two species. It is interesting to note, however, 

 that this protozoon has been reported from only five places : viz., 

 Budapest (Entz), Moscow (Wermel), Baltimore (Hegner and 

 Taliaferro), Ann Arbor (LaRue, verbally), and Charlottesville 

 (Reynolds and Looper). In each of these places they have been 

 found in great numbers during the autumn months. It seems that 

 the American forms are more pathogenic than those found in 

 Europe. Some unpubhshed data indicate that the concentration of 

 hydrogen ions influences the pathogenicity of the amoebae. 



Description: Range in length from 60/1-380/1; found on external surface 

 and in enteron of Hydra; die in from four to ten days if removed from 

 host ; usually cause death of host in about seven days. 



Class MASTiGOPHORA, Order protomonadina. 

 Costia necatrix (Henneguy) Leclerque. 



This flagellate was described by Henneguy (1883) under the 

 name Bodo necator. It was the first ectoparasitic flagellate to be 

 described, and was found in great numbers on the skin of young 

 trout. The organism possesses four flagella, a long and a short 

 pair. All of these are used in locomotion, but when attached to a 

 fish it is anchored to the epithelium by means of the long pair, 

 while the short pair are employed to draw dead epithelial cells 

 into the'cytostome. Since its discovery it has been reported from 

 the skin of fish by several investigators. 



Description: Size, 13/i x 20/i; flattened ovoid with anterior end narrower; 

 found on the outer surface of fresh-water fish. 



Nitsche and Weltner (1894) described a flagellate which they called 

 Tetramitus nitschei, from the skin of goldfish. According to these authors 

 T. nitschei differs from C. necatrix in several respects. It seems, however, 

 very probable that they were dealing with the same species, or at least with 

 the same genus. 



Class INFUSORIA, Order holotricha. 

 (a) Amphileptus hranchiarum Wenrich. 



Wenrich (1924) described this holotrichous ciliate from the gills 

 of tadpoles, where they could be seen rotating actively in a thin 

 capsular membrane. Apparently the membrane was continuous 

 with the epithelium covering the gill. It is suggested that the 

 ciliates burrow into the tissues and then gradually separate the 

 cuticular membrane from the cells beneath. 



