292 ZOOLOGY 
The mandible carries a three-jointed palp, and the maxilli- 
pedes fuse in the middle line to form an under lp. The bases 
of the thoracic limbs of the females bear on their inner surface 
a process, probably the epipodite, which projects towards the 
middle line, and with its neighbours forms the brood-pouch. 
VY, 
\ 2 
Fic. 168.—The mouth appendages of Gammarus neglectus. 
From Leuckart and Nitsche, after G. O. Sars. 
. The mandible. 
1 
2. Its palp. 
3. 1st maxilla. 
4, 2nd maxilla. 
5. Maxillipede of each side together forming an under lip. 
A little distal to this, but on the same surface, is a vascular 
process, the gill. The heart stretches through the thorax, and 
has usually a pair of valves in the second, third, and fourth 
thoracic segments. A well-developed “ fat-body” is often 
present, lying amidst the viscera. 
Certain Amphipods, as Gammarus, Orchestia, Talitrus, 
Caprella, etc., have two caeca which open into the alimentary 
canal at the junction of the mid and hind gut. These caeca, 
which stretch either backwards or forwards, contain numerous 
concretions in their walls. They have been compared to the 
Malpighian tubules of the Tracheata, but there is no certain 
evidence to show that they excrete nitrogenous waste matter 
