Our Fresh-ivater Entomostram — Chambers. 23 



or carapace, which is of a horny or coriaceous texture, and formed of 

 one or two pieces, in some approaching in appearance to a bivalve shell, 

 in others being in the form of a buckler, which completely, or in great 

 part, envelopes the body of the animal; by their having branchire 

 attached to the feet, or organs of mastication ; by their feet behig 

 jointed, and all more or less ciliated ; and by their undergoing a meta- 

 morphosis, or regular change of shell as they grow, in some amount- 

 ing to a species of transformation." 



Like other animals, they have been subdivided by naturalists into 

 families, genera, and species, according to their structural differences, 

 size, and differences in ornamentation. 



One division, the Branchiopoda, of Dr. Baird, is divided by him into 

 two orders, the Phillopoda and Cladocera. Each of these orders contain 

 several genera; but as we propose to give account only of species 

 which we have met with in this locality, we only refer to the two Phil- 

 lopoda genera, Branchippm and Edheria, neither of which is mentioned 

 by Dr. Baird, though Branchippus is very nearly allied to the beauti- 

 ful little fairy shrimp, the Chirocephcdus diaphamus, of that author. 

 We have met with but a single species of Branchippus, the B. vernahs, 

 Verrill, and that only in a single pool. In the " bottom" land, known 

 as Taylor's flats, and lying just south of Covington, ou the stream 

 euphoniously designated as " Bank Lick Creek," are numerous ponds, 

 abounding in all sorts of pond life ; but in only one of these, and that 

 one a mere puddle, but a few feet in diameter, and entirely dry 

 throughout the summer, have we met with B. vernalis. 



In this little pool it may be taken in great numbers in April. It is 

 sometliing over half an inch Ipng, white and translucent, with the post 

 abdomen or tall stained rust red, and the apical portion of the Ontenmv 

 of the same hue. The eyes are borne on short stalks above the head, 

 and it has thirteen pairs of branchiferous feet, which are constantly in 

 motion, aiding it in locomotion as well as affording it respiration. Its 

 motion is exceedingly graceful, and when a number of these delicate, 

 fragile, little creatures are placed in a glass of clear water they afford 

 a pretty and interesting sight swimming, or rather easily floating, head 

 upward, through the water. Possibly this species may prove to be 

 distinct from B. vernalis, Verrill. The allied Chirocephalm duiphanom 

 has not been discovered in this country, but is common in England 

 and on the European continent. Prof. Verrill (Sill. Am. Jour., vol. 

 Iviii., p. 244) separates from Branchippus proper two other closely allied 

 genera, under the names Branchinecta, of which he describes two 

 species from Labrador and Greenland, and Heterobranchippus. He- 

 terobranchippus was subsequently recognized as a Streptocephalus, and 

 B. vernalis made the type of a new genus, Enbranchippus. Artemia, an- 



