Fresh-water Entomostraca of South America. 



appearance and lying on each side of the body in the an- 

 terior part of the matrix, so as not to cause any perceptible 

 convexity of the dorsal face (see figs. 1, 3). 



In habits, this form on the whole closely resembles the 

 northern form Latona setifera. It was more frequently seen 

 resting on the bottom, in some corner of the aquarium, 

 partly concealed among the aquatic plants, and always lying 

 on its belly with the antennæ spread to each side. When 

 disturbed, it started away with quite extraordinary energy > 

 making several successive abrupt bounds, in which the body 

 was often seen to turn over several times. This motion, how- 

 ever, never lasted for any length of time, the animal very 

 soon again assuming its quiet attitude on the bottom. I 

 have never seen it running up along the walls of the aqua- 

 rium like L. australis, nor attaching itself to them; but it 

 always kept to the bottom, and was generally so well con- 

 cealed among the plants that it was only with great diffi- 

 culty caught sight of. When brought under the microscope 

 in a small quantity of water, the animal, as a rule, turns 

 either the ventral or dorsal face to the observer (see figs. 

 2, 3), and in this attitude very much resembles the northern 

 form, Latona setifera. In order to get a lateral view of the 

 animal, it is necessary to cause the antennæ to be reflexed 

 along the sides of the carapace (see fig. 1). This reflexion is 

 often effected voluntarily by the animal, after it has been 

 kept for some time under the microscope, though at times it 

 again forces the antennæ out to each side, which causes it 

 immediately to turn over on its ventral or dorsal side. 

 While lying in the lateral attitude, the animal remains quite 

 motionless, and accordingly admits of a detailed examination 

 even by the aid of very high magnifying powers. 



Occurrence. — The mud from which this remarkable 



