OF DENISON UNIVERSITY. 5 1 



The body is much more slender, while the viscera do not differ essen- 

 tially from D. tigris. 



GENUS MONOCERCA, Ehr. 



This genus includes elongated, nearly cylindrical or conical forms, having a 

 single greatly elongated claw and more or fewer accessory spines on the last seg- 

 ment of the foot, The maxtax is elongate, with unequal indurated ridges. The 

 stomach is oval and the intestine cylindrical. 



The only specimens of this genus as yet seen resemble very closely 

 M. rattus of Ehrenberg but are somewhat longer. The lorica is .30 

 mm. long while the claw is .22 mm. The foot consists of two seg- 

 ments, both of which are very short, while the last carries four or more 

 unequal spines. -The pulsating vessel is elongate oval but the details 

 were not studied. This rotifer it quite rare. 



GENUS DINOCHARIS, Ehr. 



The lorica is cylindrical or prismatic, with a wide opening in front. The 

 head is distinct and feebly ciliated. The eye is cervical. The foot is long, rigid, 

 and three jointed. The claws are long and the foot bears, beside these, long 

 spines anteriorly and behind. The whole shell is densely covered with granula- 

 tions or spinules. 



DiNOCHARIS POCILLUM, Eh7'. (.?) 



(Plate II. Fig. i.) 



The most abundant form of this genus in America varies so greatly 

 in both size and details of structure that one is tempted to identify it 

 with the most frequent species of Europe in spite of variations from 

 the descriptions of authors. The outline of the lorica is cup-shape 

 and its symmetry is broken by two ridges near the posterior edge, pass- 

 ing transversely. It is 1 1-5 times as long as wide. The first segment 

 of the foot is short and bears two long curved spines above. The 

 middle joint is twice as long and nearly cylindrical. The third seg- 

 ment is about as long as the first and bears two curved claws four 

 times as long as the segment and also a short spine about as long as 

 the segment. 



The whole body is about . 24 mm long, including the claws, which 

 measure . 08 mm. The eye is large and is seated on an ovoid ganglion. 

 The ovary is large and the nuclei are quite distinct. The egg is 

 obliquely placed and nearly as long as the width of the lorica. Two 

 curved elliptical glands lie in front of the stomach. The lateral ves- 

 sels of the vascular system are large. Encountered only in Minnesota. 



