332 Illinois State Laboratory of Natural History. 



round mouth-opening at the base of the snout. A row of 

 cilia extends along each side of the band of trichocysts and 

 around the mouth ; ciliation of body fine and uniform. 



59. D. anser 0. F. Mull. 



Taken once, in August, with the Birge net, in vegetation 

 on the west side of the river at E. 



Family CHLAMYDODONTID^. 



Subfamily NASSULiN-ffi. 



Nassula Ehrbg. 



Oval or somewhat elongate, ends equally rounded ; mouth 

 circular, situated on the ventral surface back of the anterior 

 extremity, left side more or less constricted beside the mouth ; 

 a row of stronger cilia extending from the mouth along the 

 constriction ; body finely and evenly ciliated, usually highly 

 colored, with a pigment spot at the constriction. 



60. N. ornata Ehrbg. 



Found once, in an aquarium started with dried mud from 

 Phelps Lake. 



Order TRICHOSTOMATA. 



Suborder ASPIROTRICHA. 



Family PARAM^CIID^. 



Paramecium 0. F. Mull. (Slipper Animalcule.) 



Ovate to elongate, flexible; densely, finely, and evenly 

 ciliated ; peristomal groove feebly or moderately excavated, 

 narrowing posteriorly, and ending in the oval mouth, which 

 is in the middle part of the ventral surface; one or two 

 stellate contractile vacuoles. 



61. P. aurelia 0. F. Mull. 



Very few individuals of this common species were found, 

 possibly because of the lack of stagnant water at any of the 

 substations. A few were taken among vegetation and in 

 towings in August, and examples appeared in towings in 

 October and January, all in the main river. 



