THE CYTHERE IMPRESSA. 



637 



surface ; for as soon as the shell is exposed to the air, it becomes quite dry, and so 

 buoyant that no exertion of the Cypris can sink it again. 



These tiny animals will often live through a hot summer which dries up the pond in 

 which they reside, and at the first rain will make their appearance again, swimming 

 merrily about as if nothing had happened. As soon as they feel themselves being 

 deserted by the water, they bury themselves deeply in the mud, and even their eggs 

 retain their vitality, though the mud should be baked quite hard. When the Cypris 

 changes its skin, it throws off the whole shell, the internal parts of the body, the beau- 

 tiful comb-like gills, and the tiny hairs which clothe the bristles of the antennae. 



Two more examples of this pretty genus are given in this illustration, fig. B repre- 

 senting Cypris clavdta and fig.C, Cypris vidua, seen from above, in order to show the 

 two valves of the shell and their line of junction. Seventeen or eighteen British species 

 of Cypris are known. 



In the family of Cytheridce, the upper pair of antennae have no long filaments. 



A. Cypris tristriata. B. Cypris clavata. 



E. CytJiire inopinata. F. Cythereis Jane sit. 



I. Canthocamptus ininutus. 



C. Cypris vidua. D. Cytfttre minna. 



G. Cythire impressa, H. Cypridina Macandrei. 

 K. Cetochilus septentrion&lis. 



The members of the typical genus Cythere are mostly marine, and may be found in 

 the little rock-pools at the sea-side, darting about among the branches of sea- weeds and 

 zoophytes that live so plentifully in such situations. Safe in these sheltered spots, 

 they care nothing for wind and waves, and the storm which flings the huge whale on 

 the shore will fail to injure these tiny beings, whose very minuteness is their safety. 

 Three species of Cythere are here given. Cythere minna, fig. D, is remarkable for being 

 the largest British species seen by Dr. Baird. Its valves are white. It was found in 

 deep water off Shetland, and taken in a dredge. Cythere inopinata, fig. E, derives its 

 specific name of inopinata or unexpected, from the fact that the creature was found 

 where no one would have expected its presence, namely, in a small pond in Middlesex. 

 It is a very small species, and always remains at the bottom. Its color is white, and 

 there is a little orange-colored mark on the upper edge. An oblique view of this 

 species has been chosen, in order to show the curious rounded projections upon the 

 middle of each valve. 



The Cythere impressa, fig. G, was found in sand at Torquay. The shell is dull black 

 in color, and is covered with little punctures impressed upon its surface, whence is 

 derived its specific name. 



