quite rudimentary, not reaching even to the extremity of the 

 penultimate joint. 



The 1st pair of maxillae exhibit in their terminal part (fig. 

 6) well-marked differences from those organs in the genus Steno- 

 eypris. The palp is much coarser, its first joint being consi- 

 derably dilated towards the extremity, which anteriorly juts out 

 as a rounded prominence beset with a fascicle of rather strong 

 ciliated setse. The terminal joint of the palp is very short, 

 broader than it is long and somewhat obliquely truncate at the 

 tip, which is armed with about 6 partly spiniform setse. The 

 masticatory lobes are unusually short and thick, and the outmost 

 has, besides the apical tuft of bristles, a very thick and densely 

 ciliated seta affixed to the anterior edge. 



The 2 pairs of legs do not seem to differ materially from 

 those in Stenocypris, except that the latter are somewhat less 

 elongate. 



The caudal rami (fig. 5 and 7) are quite symmetrical and 

 very narrow, almost linear, though a little broader at the base. 

 The claws are rather slender and at first sight appear quite 

 smooth. On closer examination, however, by the aid of a very 

 strong magnifier, 'their concave edge is found to be beset with 

 extremely small denticles, which also occur along the dorsal edge 

 of the ramus. ( )f the claws the apical is a little (about V*) 

 longer than the other, but does not attain the half length of 

 the ramus. The seta of the dorsal edge, placed at a short dis- 

 tance from the upper claw, is rather small, scarcely longer than 

 the apical, which does not quite reach the half length of the 

 terminal claw. 



Biological Observations. — Of this form I have been euabled 

 to examine great quantities of specimens and during a rather 

 long period. The species at first, appeared at the beginning of 

 ^September 1886 in two of my aquaries, the same in which Ste- 

 nocypiis malcolmsonii was found. The specimens were at that time 

 not very numerous, and in one of the aquaries they were only 

 observed that year. In the other, however, the water of which 

 I had allowed to evaporate at the close of the autumn, the spe 



