74 DAVENPORT ACADEMY OF SCIENCES. 



extension. The left-hand margin of the body nearly straight. 

 Oral system as in CJulodou iucullulus. Nucleus oval, posterior to 

 the middle of the body. Contractile vesicles numerous and 

 scattered. 



lycngth, 75 microns. (Fig. ii6, PI. XV.) 



Not a common species in this state but has been found in John- 

 son county, taken from a fresh water pool among algae and other 

 aquatic plants. 



^GYRIA C. & Iv. 



Body enclosed within two valves, which are united on the dor- 

 sal border. A tail-like process extending from the posterior 

 extremity. Oral aperture ventral, a short distance from the 

 anterior end, followed by a tube-like pharynx. 



^GYRIA Sp. (?) 



Figure 117, Plate 15, illustrates a form observed but once in 

 this state and tentatively placed under this genus. 



From a lateral point of view the body is a little longer than wide, 

 even and broadly rounded at each extremity. Right valve 

 traversed by three longitudinal ridges. Posterior caudal projec- 

 tion short, thick, and bluntly rounded, directed obliquely. 



Length of valves, 175 microns. 



Found in pond water in Johnson county during the fall of 

 1903 and not observed since. As far as I have been able 

 to determine nearly all species of this genus previously described 

 are reported as inhabiting salt water, but the study of this fresh 

 water form, although somewhat brief, revealed generic characters 

 which would place it within this genus or a very close ally. 



Family, CHII^IFERID^. 



TRICHODA Miiller. 



Ovate, elastic, anterior extremitj^ narrow with border obliquely 

 truncate, rounded posteriorly. Oral aperture terminal, provided 

 with a minute vibratile membrane. Cilia very fine. 



Trichoda pura Ehr. 



Body elongate-oval, broadly and evenly rounded posteriorly. 

 Anterior extremity curv.ed, narrow, and almost pointed. Nucleus 



