OF DENISON UNIVERSITY. 57 



backward. The foot consists of three slender joints, the last of which 

 bears two lanceolate appendages somewhat longer than the segment 

 preceeding. The whole shell is covered with minute points. The 

 trochal disc is broken up into five lobes and the cilia are of two sizes. 

 The measurements of one specimen are given as illustrating the pro- 

 portions. Length .20 mm. exclusive of foot, width .14 mm., termin- 

 al stylets .024, lateral, posterior spines .028 mm., anterior spines about 

 .04 mm.. From the side, the ventral surface (in outline) is seen to be 

 plane while the dorsal is composed of two inclined planes (or is 

 "humped.") The foot is moved by two pairs of muscles. The con- 

 tracting vessel is unusually large. I'he maxtax and the position of the 

 viscera seem to be as in other species of Brachionus. The animal 

 seems most to resemble B. niilitai-is, Ehr. of the European species. 



PlCESOMA LENTICULARE, geil. Ct Sp. 71. 



(See figures facing Index.) 



The animal for which the above generic name is proposed, was 

 several times seen in a gathering taken at the reservoir near Hebron, 

 Ohio, in November. The general form is very similar to that of 

 many minute bivalved Crustacea [Chydorus)^ with which it was asso- 

 ciated. The lorica is composed of two ovate valves, which are par- 

 tially united below, so that the foot springs from the middle of the 

 ventral margin. The animal is laterally compressed. On the dor- 

 sal aspect of the lorica are several distinct ridges arranged about as 

 follows : A pair of short transverse markings occupy a point poste- 

 rior to the middle of the dorsal aspect ; anterior to these, and begin- 

 ning at either end, spring diverging lines which lead to notches of the 

 anterior margin; behind, two ridges lie on either side the median line 

 and extend to the acute posterior end of the shell. Several lines 

 border the above described markings on either side and are approxi- 

 mately parallel to the axis of the body. Seen from the side, the lor- 

 ica is elliptical and is truncate in front and acute behind. The dorsal 

 line is a uniform curve, while the ventral is prominent near the middle 

 at a point some distance in front of the point of union of the valves. 

 Seen from above, the front half is quadrate, while the posterior half is 

 triangular. The lorica is lenticular, considered as a whole, and is 

 marked by minute hexagonal or irregular depressions. 



The head is armed with two long sensory organs and has two sorts 

 of cilia. The outer series is quite feeble, but the ventral prominence 



