Cope.] 14:0 [March 20, 1874. 



the adjacent banks. Observations on a pool of this kind determined 

 sixteen species which lived in or on the water, which had an area of 

 thirty feet by fifteen,' and a depth not exceeding a foot. Three of the 

 sjiecies were worms, six insects, one arachnid, and eight crustaceans. 



The insects were a bluish fly, with a pale bloom, which ran rapidly 

 over the surface, aiding its progress by its wings ; a slender beetle, that 

 clung to the submerged stems ; two species of actively swimming water- 

 beetles, one beautifully varied with white ; and a sluggish, pale-green 

 species, which swam readily. There was also that cosmopolitan boatman 

 who swims on his back, the hemipterous notonecta. One of the worms 

 was delicately striped with lines and rows of dots, another was soft and 

 jointless, and could contract itself into a mere lump or extend itself to 

 considerable length. It was no doubt a planarian, and was of a pea-green 

 color. Aiiother planarian was white, and some of its internal organs 

 showed as a milk-white zigzag figure through the body walls. It swam 

 freely through the water. Of the crustaceans, four were the shelled Gy- 

 prides. One was very small, short oval, and green ; another, still small, 

 was a long oval, straw-colored, and covered with hair ; a third was large 

 as a small pea, almost globular, and brilliant green. It was very abund- 

 ant, swimming in twos and threes among the grass-stems or near the sur- 

 face. The fourth was a gigantic species, large as the thumb-nail, and of 

 a pale-reddish orange color. It was frequently observed in encounters with 

 others of its species. The water was alive with shoals of what appeared 

 to be at first sight the translucent fry of some fish. On closer examination 

 they proved to be elongate crustaceans allied to the Branchipus, their 

 delicately-fringed gills hanging suspended from the hinder segments of 

 the body. They were covered with a jointed coat of mail, and darted 

 about with great activity. They were elegant creatures, with a crimson 

 tail setting off the glass-like clearness of the body. The most singular 

 of these forms is the Cyclops. It resembles superficially the king crab 

 of our sea-shores, truly, indeed, in the great buckler or shield covering 

 the head and thorax. It has a single elevation on the middle of the top 

 of the head for two eye windows or cornese, and an inferior pair of widely- 

 separated eyes look downward to the bottom of the water. The tail or 

 body is soft, jointed, and worm-like, and bears a pair of feelers at the 

 end. These curious creatures swim on the bottom, chasing each other 

 here and there, resembling in their motions and form diminutive cat 

 fishes. Some other forms were minute crimson, and strangely formed 

 creatures. The common arachnid was a round-bodied Hydraelina, or 

 water- tick, of a bright red color. 



This population evidently has a short life, and it is probable that their 

 existence is only secured by the long preservation of the eggs in the 

 bottom of the dry ponds, which may be readily carried from place to 

 place by winds during the dry season. 



