PHYLLOPODOUS BRANCHIOPODA. 117 



The second principal section of the Branchiopoda is named 

 PHYLLOPODA, from the legs, which vary in number from 

 twenty to more than a hundred, being flattened, the joints 

 forming ciliated plates. They have a pair of eyes, and the 

 antennae, of which there is generally only a single pair, are 

 small, and not fitted for swimming. This section is divided 

 into two principal groups. 



1. The Ceratopthalma, having the eyes generally carried 

 upon footstalks, ten or twenty-two pairs of legs, the anterior 

 neither much longer than the remainder, nor branched. The 

 eggs are either internal, or carried in a sac at the base of the 

 abdomen. (Branchipus, Limnadia.) 



In the genus Branchipus (Latreille, Chirocephalus Jur.), 

 the body is narrow, long, and compressed, the head dis- 

 tinct, with two horns between the eyes, eleven pair of legs, 

 the abdomen long and cylindric, with two terminal ciliated 

 plates. The males are distinguished by a pair of very large 

 horns attached to the mouth. The eggs are borne by the. 

 females in a pouch attached to the base of the abdomen. 



Jurine, Prevost, and Dr. Shaw, have given very full accounts of 

 the structure and habits of these animals. When full grown they 

 are about an inch and a half long, and are found occasionally iu 

 great numbers in small puddles of standing fresh water. They 

 swim well upon their backs, and their legs, which are incapable of 

 assisting locomotion, are kept in a constant undulatory movement, 

 which has for its object the forming of a current of water between 

 the base of these organs, and which, following the canal of the 

 breast, conveys to the mouth the small particles upon which the 

 animal feeds. The eggs are yellowish coloured ; they are at first 

 round, but afterwards assume an angular form, which favours their 

 preservation, since it appears that they are enabled to withstand a 

 very considerable degree of drought until a fall of rain sufficient 

 to cause them to hatch takes place. On quitting the egg the body 

 is divided into two globular masses, the anterior of which com- 

 prises a single eye, two short antennae, two large branched organs 

 serving for swimming, and two short and slender legs. After 

 shedding their skin the first time, they have three eyes, the middle 

 one being smooth ; the hinder part of the body is elongated, and 



