I06 DAVENPORT ACADEMY OF SCIENCES. 



This organism is solitary in its habits and has rarely been ob- 

 served in this state. Habitat, fresh water among algae. When 

 contracted the peristome is tightly closed and a small conical pro- 

 cess appears in the central region of the anterior margin; at the 

 same time the body is thrown on its side, the concave surface 

 being folded. 



SCYPHIDIA sp. 



Body elongate, cylindrical, contractile, wider anteriorly, grad- 

 ually tapering toward the narrow posterior extremity. Ciliary 

 disc slightly elevated. Posterior half of the body furrowed trans- 

 versely, anterior half smooth. Contractile vesicle anterior. Body 

 pyriform when contracted. 



L,ength of extended body, 50-75 microns. (Figs. 180-181, PI. 

 XXV.) 



This species above described and referred to this genus has been 

 found in Poweshiek county. Habitat, fresh water. So far as can 

 be determined, I find no described species corresponding to the 

 funnel-shaped contour and posterior transversely striated region 

 of this organism. 



VORTICEIvLA Linnaeus. 



Body more or less bell-shaped, attached by an elongate, con- 

 tractile stalk. Peristome usually prominent. A series of strong 

 cilia encircle the central elevated region or ciliary disc, the right 

 extremity of the series descending into the oral opening, which 

 is eccentric in position between the peristome and the ciliary disc. 

 Pharynx usually conspicuous. Nucleus band-like, curved. Sur- 

 face smooth or transversely striate. Contractile vesicle in the 

 anterior region. 



All members of this genus are similar in general features, mak- 

 ing it somewhat difficult to recognize separate species. However, 

 variations of the form of the bell, and the character of its surface, 

 positions of the ciliary disc, size and length of the stalk, are char- 

 acters which are of assistance in distinguishing one species from 

 another. Although many forms are social to a remarkable de- 

 gree, colonies are never built up, longitudinal fission resulting in 

 the complete liberation of one-half of the dividing zooid. The 

 separated individual having previously developed a posterior 



