638 THE HERRING-SHRIMP. 



A closely allied genus is represented at fig F. and is remarkable for the manner in 

 which the valves are ridged, irregular, covered with tubercles, and having their edges 

 boldly toothed. This species was taken in the Isle of Skye. 



In the family of Cypridinadas there are two eyes, set as footstalks, and two pairs 

 of feet, one pair being always within the shell. There is only one genus of these creat- 

 ures, and all the species are marine. The shell is oval, sharply pointed at each end, 

 and the front edge is deeply notched. The pair of feet that are retained within the shell 

 are modified into one organ, which seems to be intended for the purpose of supporting 

 the eggs. At fig. H is seen this curious organ. The present species was procured in 

 seventy fathoms of water, near the Isle of Skye. Some of the exotic species are 

 luminous. 



The next order is termed the Copepodae or Oar-footed Entomostracans, because the 

 five pairs of feet are mostly used for swimming. The body is divided into several rings, 

 the cuirass covers both the head and thorax, and the mouth is furnished with foot-jaws. 



In the family of the Cyclopidae the head and body are merged together with the first 

 ring of the thorax. There are two pairs of foot-jaws, and the fifth pair of legs are very 

 minute. 



The species which is represented at fig. F on the illustration at page 635 is very 

 common in every pond and ditch, and the female may at once be recognized by the 

 little egg-bag which she bears on the sides of the abdomen, like John Gilpin's wine- 

 bottles at his belt. The color of this species is exceedingly variable, differing according 

 to the locality where the creature happens to reside. It is mostly white, but some 

 individuals are brown, others greenish, while a few are red. Both salt and fresh water are 

 inhabited by the CYCLOPS, and some of the marine species are so highly luminous, that 

 they add in no slight degree to the phosphorescence of the ocean. At figs. G and H are 

 shown specimens of the young in two stages of their growth. 



TURNING again to the engraving on page 637, and referring to fig. I, we find a little 

 ceature with a long abdomen, which it is able to turn over its back, something after the 

 fashion of the earwig or the cocktail beetles. In this Canthocamptus the thorax and 

 abdomen are merged into each other, and gradually diminish in size to the extremity. 

 All the species belonging to this genus have very small and simple foot-jaws. It inhabits 

 ponds and ditches of fresh water. Mr. Tuff en West tells me that in February, 1861, he 

 was examining some of the slime that had gathered upon the roof of the Cramlington Pit, 

 at a vast depth from the surface, and that he found in the slime some of these minute 

 crustaceans quite brisk and lively, whisking their tails up and down smartly, as shown 

 in the figure. These creatures must have been washed down the pit while still 

 unhatched, and have been thus carried down from the open air into the bowels of the 

 earth. 



Fig. K represents a creature, which though very small, not more than a sixth 

 or seventh of an inch in length, is of exceeding importance to commerce, as it affords 

 food to the herring, several whales, and other valuable beings. In the seas where 

 this little creature lives, whole tracts are reddened with the multitude of their hosts, 

 which swarm near the surface, and congregate in such vast numbers, that the wind has 

 been known to catch up a whole bank of them, like a wave, and fling it into the vessel, 

 covering the deck and the sailors with their bodies. The codfish feeds largely and 

 luxuriously upon these abundant creatures, heeding not to take any pains about them, 

 but swimming lazily through their masses and opening its mouth, into which they pass 

 without the least trouble. 



The long antennae are used as oars, being thrown backward at every stroke until their 

 tips touch each other. This attitude, however, is only assumed while the creature is in 

 haste, as it is often seen to pass gently through the water, with antennas at right 

 angles to the body, as shown in the engraving. Dr. Sutherland, in his " Voyage to Baffin's 

 Bay," writes of these elegant little beings : " They are always on the alert to elude and 

 escape from their pursuers. When the water is but slightly agitated, they dive from the 



