296 ZOOLOGY 
gives off a vessel which supplies the head and its appendages ; 
both the aorta and the heart also give off lateral branches, 
which supply each segment. No antennary gland is present. 
Asellus, like the majority of Isopods, is dioecious. The 
ovaries consist of two sacs, entirely independent of one another, 
which occupy the thorax, and extend into the abdomen, A little 
behind their middle point, in the fifth free thoracic segment, a 
Fic. 172.—Asellus aquaticus. 
Male viewed from above. 
From Leuckart and 
Nitsche, after G. O. Sars. 
1. Anterior antennae. 
(ih A 
2. Posterior antennae. 
pairs 
LY 
ae To 
ore Thoracic limbs. \s! y/| S 
10. The last pair of abdom- ZAR PS ke 
inal limbs. 
, h 
G4 
ha —~ 
11. Testes with their efferent 
canals, 
\ 
NY 
y 
The nervous system is shown 
black. 
short oviduct descends from the ovary, and opens on the sternum 
of that segment; this oviduct seems also to function as a recep- 
taculum ovorum; at their exit the ova pass into the brood- 
pouch formed by oval lamelliform processes (oostegites) borne 
by each of the four pairs of anterior walking limbs. 
