LIGEA, 71 
this forms a true posterior lip. The maxillary excretory 
organ opens at the base of the second maxilla. 
The seven segments of the thorax form the greater part 
of the animal’s body. They are convex on their anterior 
margins and concave behind. The lateral portions form 
large epimeral plates, obtusely acuminate, and directed 
backwards. The segments slightly overlap, and the 
uniting membrane, which is not impregnated with 
calcareous salts, sinks into the hypodermal tissues. On 
the ventral sides, where the epimera join the body, the 
walking legs or pereiopods arise. The first three pairs 
of pereiopods are approximately the same size, the last 
four pairs gradually increase in size. The ventral wall 
of the thorax is thin and transparent, and strengthened 
by slightly curved transverse bars. On the ventral side 
of the thorax cf the female, the brood-pouch full of ova 
is very conspicuous in the breeding season. It is formed 
by lamellae which arise inside the origin of the five 
anterior pairs of thoracic appendages and grow ventrally, 
overlapping the adjacent lamellae distally and laterally. 
The paired female genital apertures are situated on the 
inside of the fifth pair of pereiopods. The male genital 
products are ejected through a pair of styhform 
appendages on the posterior border of the last thoracic 
segment, immediately in front of the branchiae. 
The metasome or abdomen consists of five segments 
and the telson, and is about a third of the entire length 
of the animal. The two anterior segments are narrow, 
and do not reach the margins, but are lodged in the 
concave posterior border of the seventh thoracic segment. 
The three posterior segments have their lateral margins 
produced into tooth-like backwardly projecting processes. 
Five pairs of uropoda, which are of the nature of 
branchiae, are borne on the ventral side of the abdomen. 
