176 ROBERT W. HEGNER. 



referred to here as Species B, probably were present in all of 

 many Rana pipiens tadpoles collected when about 9 weeks old. 

 They were recorded incidentally in 32 of them, although very 

 little attention was devoted to them at the time. They were 

 noted also in five large tadpoles of the green frog but were proba- 

 bly also of general occurrence in this species. Species B is a 

 cylindrical, elongate species with a blunt anterior end and a 

 posterior end terminated either by a short subacute tip or by a 

 longer process which is slender, pointed at the tip and slightly 

 curved. No free swimming forms were seen but most of the 

 specimens were undergoing slow metabolic movements. Speci- 

 mens ranged from 99 /x to 128 /x in length and from 9 M to 16 /JL 

 in breadth, w r ith an average length of no ju and average breadth 

 of 12 /.i. A single short flagellum that moved too slowly to dis- 

 turb the particles in the surrounding medium was observed in 

 several specimens. Numerous disciform green chromatophores 

 and a large reservoir and red stigma are present. The periplast 

 is spirally striated and strongly punctated in some specimens. 

 In many respects it resembles Englena spirogyra Ehren. Fig-4 

 is a camera lucida sketch of a living specimen magnified 1600 

 diameters. 



Euglenoids of Species B were never numerous in any tadpole. 

 They were more often observed in the intestine than in the 

 rectum. Their ability to live in these environments and their 

 frequent occurrence indicate that they are normal inhabitants 

 of the digestive tract of tadpoles. An attempt was made to in- 

 crease their numbers by feeding the rectum and intestine of in- 

 fected tadpoles to other infected tadpoles. Thus the digestive 

 tracts of 22 tadpoles were fed to four tadpoles of Rana pipiens 

 on July 4. Not fall of this food was eaten and after 24 hours 

 living active specimens of both Species A and Species B were 

 observed within the walls of the intestines and recta offered as 

 food. Specimens were still alive and active after 48 hours. One 

 tadpole was killed and examined after an interval of three days 

 (July 7) and the remaining three after six days (July 10) but no 

 increase in the numbers of Species B could be ascertained with 

 certainty. I believe there was an increase but the actual numbers 

 were too small to determine the point definitely. 



XI. Species of the Genus Phacus. In a few of the tadpoles of 



