Tank No. 4. 
63 
pore, passing from the oiie to the other through innumerable gill-slits in 
the throat, on the walls of which vibrating hairs drive the water along; an 
outgoing chamber surrounding the throat and communicating with the 
Fig. 108. Phallusia mammillata, Fig. 109. Four specimens of Ciona in- 
Y 2 nat. size. testinalis, l /% nat. size. 
outgoing pore. Into this chamber the eggs and excrementa are also dis¬ 
charged, the intestine being coiled in the comparatively small solid part 
of the body. 
Fig. 110. Four specimens of Cynthia Fig. 111. A colony of Diazona vio- 
papillosa , 1/2 nat. size. lacea, l/ 3 nat. size. 
The Ascidians are nearly all sessile animals; they either remain 
separate individuals like the above described Phallusia, the semitrans¬ 
parent Ciona (Fig. 109) and the crimson- or orange-coloured Cynthia 
(Fig. 110); or they form colonies in whifeh the individuals are connected 
