336 Illinois State Ldhoratory of Natural History. 



and Quiver Lake. In the following year it was again noted 

 in small numbers, during August and September, in towings 

 from the river at E. 



CODONELLA HaecKEL. 



Lorica indurated, short-urceolate in form, composed of 

 hexagonal or circular areolets, each with a darker central dot ; 

 structure usually more or less obscured by a covering of 

 foreign particles, a slight constriction at the base of the 

 neck of the lorica ; peristomal cilia often altered into leaf-like 

 lamellcTB. 

 73. C. cratera Leidy. 



Difflugia cratera Leidy. 

 Few species among the Infusoria, attract so much attention 

 as this. It was frequent to abundant in towings from the 

 deeper and more permanent bodies of water under examina- 

 tion, continuing apparently throughout the year. At Thomp- 

 son's Lake it was abundant in December, and again in 

 February was found in a towing from under eighteen inches of 

 ice. On one occasion in the latter part of August six tow- 

 ings were taken in different parts of Matanzas Lake and 

 examples of C. cratera were found in all but one of these 

 towings. This lake is fed almost entirely by springs, and con- 

 sequently the water is in places comparatively cool during the 

 summer, thus affording a congenial habitat for species that 

 thrive best in cold waters. One towing was taken near the 

 point where the water from a large spring enters the lake, and 

 contained an abundance of this form. The species serves 

 as food for such rotifers as As-planchna and AsjAanchnopu.s. 



Section Hypotricha. 



Family OXYTRICHIDiE. 



Subfamily Pleurotrichin^. 



Stylonychia Ehrbg. 



Free-swimming, persistent, obovate or elliptic, peristome 

 not greatly narrowed ; anterior styles usually eight, occupy- 



