CHARACTERS OF THE CUMACEA 293 
creatures, and he therefore found them.’ Some years 
earlier Milne-Edwards had indeed described a species as 
having two eyes, which almost certainly has but one; so 
easily are even the ablest naturalists misled into taking 
for granted that what is customary will prevail. A very 
few of the Cumacea have two eyes. The majority have a 
single median eye, but occasionally the elements of this 
compound organ are so arranged as to have the appear- 
ance of several distinctly separated ocelli. 
‘The Cumacea are said to leave the egg as maggot- 
shaped Nauplii. From the maternal pouch they issue 
almost in the adult form, only being as yet without the 
last pair of trunk-legs or perzeopods, a deficiency which 
in two species, Campylaspis nodulosa, Sars, and Leptostylis 
manca, Sars, is perhaps persistent. The notion that these 
creatures, which are in truth born almost fully fledged, were 
only larval forras, was early disproved by Goodsir and 
Kroyer, but was nevertheless still upheld for several years 
by three of the most distinguished naturalists of the 
century. 
In no group of the Malacostraca is the general form 
more characteristic than here. This is principally due to 
two unvarying features, the narrowness of the pleon and 
the prominence of an elongate pair of uropods at its ex- 
tremity. A distinct telson may or may not be present; 
of the six preceding segments none is ever wanting, and 
of these the fifth, without any trustworthy exception, is 
the longest. The front part of the body is always more 
bulky than the pleon, and sometimes enormcusly so. The 
integument is often stoutly crustaceous, more ready to 
break than to bend. 
Normally there are five segments of the trunk distinct 
behind the carapace, carrying respectively the five pairs of 
pereeopods. Occasionally, however, the first of these five 
segments is absent or rudimentary, and in one genus the 
third and fourth segments are coalesced. Sometimes the 
carapace overarches one or more of the free segments. More 
or less completely sheltered beneath the carapace lie all 
the organs from the eyes to the third maxillipeds. There 
