OA eae 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 brachyura 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 
Fia. 5.—Ohirocephalus diaphanus, male. Side view of head, showing the large second 
antenna, Ay, with its appendage Ap, above which is seen the filiform first antenna ; 
D.O, dorsal organ ; #,, 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 Branchipus and its allies they 
are simple unjointed rods, in some species of Artemia they are 
three-jointed, in Apus they are feebly divided into two joints, 
while in Hstheria 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 
