ORDER ACALEPHA SIMPLICES. 487 
fluid in motion, which is seen to pass into two lateral tubes, 
that soon subdivide each into four branches, and terminate on 
the surface of the body, by opening into longitudinal canals. 
Through these canals the fluid is conducted into the cilia, 
which are constantly in motion, and appear to be respiratory 
organs. Finally, from the sides of each of the eight costal 
canals, spring an infinity of small vessels, or transverse sinuses, 
which establish a communication between them, and which 
sink into the surrounding parenchyma. On each side of the 
spheroid, and internally, we perceive two small masses which 
occupy each the bottom of a cavity or cul-de-sac, and give 
birth to two long contractile filaments, issuing through two 
circular apertures, situated towards the inferior third of the 
body. ‘These filaments are subsequently divided into a great 
number of branches. 
To this genus have been referred some more simple species, 
which merely resemble a sac, furnished with ciliated ribs, and 
open at the two ends. Ipya. Oken. Bere ovatus Brug. 
or Medusa infundibulum, Gm. 
There are some which are even destitute of ribs, and whose 
form represents that of a band without bottoms. DoLIoLuM. 
Otto. D. Mediterraneum, Otto. 
CALLIANIRA, Peron, do not appear to differ from Beroe, 
except in having much more projecting ribs, united two by 
two, to form two sorts of wings. Their internal organization 
is not sufficiently known. Callianira didiploptera, Peron. 
JANIRA, Oken., appear to be akin to the callianire ; but on 
each side there are three large ciliated ribs, and two long fila- 
ments divided into branches. Beroé hexagone, Brug. Encyc. 
vers. pl. 90. f. 6. 
ALCINOE, Rang., have the body cylindrical, open at one 
extremity, furnished on the other with two large wings, which 
by being folded over it, can envelope it altogether. Its cylin- 
drical part is flanked with four projecting ribs, each termi- 
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