CRUSTACEA BRANCHIOPODA 



CHAP. 



pressed and produced, on each side of the anus, into a flattened, 

 upwardly curved process, sharply pointed posteriorly, and often 

 serrate ; the anal lobes are represented by two stout curved spines, 

 while in place of the dorsal prolongation of Lepidurus we find two 

 long plumose setae above the anus. In the characters of the telson 

 and anal lobes, as in those of the head, the Limnadiidae approxi- 

 mate to the Cladocera. In Limnetis Irachyura the ventral face 

 of the telson is produced into a plate projecting backwards below 

 the anus, in a manner which has no exact parallel among other 

 Crustacea. 



The appendages of the Phyllopoda are fairly uniform in 



Fio. 5. Chvrocephalus tliaplnnnts, male. Side view of head, showing the large second 

 antenna, A. 2 , with its appendage Ap. above which is seen the filiform first antenna : 

 U.O, dorsal organ ; 1; median eye. 



character, except those affected by the sexual dimorphism, which 

 is usually great. 



Of the cephalic appendages, the first antennae are generally 

 small, and are never biramous ; in Bmnchipus and its allies they 

 are simple unjointed rods, in some species of Artcmia they are 

 three-jointed, in Apus they are feebly divided into two joints, 

 while in Esthcria they are many-jointed. The second antennae 

 are the principal organs of locomotion in the Limnadiidae, where 

 they are large and biramous; in all other Phyllopoda they 

 are uniramous in the female, being either unjointed triangular 



