14 G. o. SARS. [No. 7. 



which respect it exhibits very considerable resemblance to La- 

 tona setifera or still more perhaps to Acanfltoleheris currirotfris 

 (Muller). Like both of those Northern species, it is a true limi- 

 cole form, hiding itself with great dexterity in the loose bottom- 

 deposit, from which it only now and then emerges to make a 

 short trip through the water. This swimming motion is exceed- 

 ingly rapid and effected by sudden jerks, whence it happens, 

 that the body will often revolve several times before reaching 

 the bottom. Sometimes I have seen it darting up the walls of 

 the aquary, now and again fixing itself for some time together 

 to the very same spot, with the head invariably turned upwards. 

 The elongate diverging setae of the infero-posteal corners of the 

 valves may indeed be of some service during the movements, 

 being then spread out in a radiating manner. As well known, 

 similar setae, affixed precisely in the same manner, also occur in 

 the two above mentioned Northern Cladocera, that show such 

 great resemblance in habits with the present form. Moreover, 

 the anomalous position of the eye in this animal, as well as in 

 Latona setifera, may, I think, be easily accounted for by the 

 strongly marked burrowing habits of both these forms, the body 

 resting at times for the greater part deeply immerged in the 

 loose mud, with only the dorsal surface more or less uncovered, 

 whence the eye, if located in the usual place, would be com- 

 paratively inoperative. Placed under the microscope, the animal 

 generally turns the upper or lower face to the observer, the 

 strongly diverging antennae preventing it from assuming a lateral 

 position. Only when the antennae become reflexed and closely 

 appressed along the sides of the valves, is it possible to turn the 

 body so as to get a lateral view of the animal. This reflexion 

 of the antennae takes place as a rule spontaneously after some 

 time, especially when the quantity of water surrounding the ani- 

 mal is very small. In some cases only does one of the antenna? 

 become reflexed as aforesaid, the other retaining its original ex- 

 tended position (see fig. 1). 



After a few days, the specimen had discharged its young 

 brood, and I was much interested in watching the minute am 



