PHYLLOPODA. 281 
Mollusca But they are especially characterized by the 
road leaf-like feet, subdivided into lobes, and adapted for 
breathing as well as 
for swimming The 
thorax merges insens- 
ibly into the abdomen. 
The number of body- 
segments varies great- 
ly, there being six- 
teen in Limnetis, the 
simplest form, and 
sixty-nine in Apus, 
or three times the 
number present in the 
lobster, the segments _ Fig. 238—Limmetis Gouldi#, much enlarged.—After 
thus being irrelatively P™™=°** 
repeated, a sign of inferiority. There is a pair of simple 
eyes consolidated into one as in Limnetis and Limnadia, or 
as in Apus, there is a 
pair of compound eyes, 
situated in the cara- 
pace, apparently on 
one of the antennal 
segments. In Bran- 
S= chipus and Artemia 
the compound eyes 
are stalked, an antic- 
ipation of the stalked 
eye of the lobster, 
etc., but the eye, it 
should be noticed, is not developed from a separate 
segment, but from one of the two antennal segments. All 
the members of this order hatch in the Nauplius form, the 
three pairs of appendages of the larva, representing the two 
pairs of antenne and the mandibles of the adult. The spe- 
cies live in pools of fresh water liable to dry up in summer ; 
they lay eggs which drop to the bottom, and show great vi- 
tality, withstanding the heat and dryness after the water 
has evaporated ; the young hatching after the rains refill the 
pools or ditches. 
Fig. 289.—Limnadia Agassizii, enlarged. 
