380 ACALEPHA, 
XC, 3, 4. Body spherical and with eight ribs; two ciliated 
tentacula susceptible of great elongation issuing from its infe- 
rior extremity(1). Itis very common in northern seas, and even 
in the British channel; the Whale is said to feed on it(2). 
Naturalists have referred to the same genus, simple species— 
Ipya, Oken—which are merely in the form of a sac furnished with 
ciliated ribs and open at both ends(3). 
Some—Dotto._um, Otto—are even destitute of ribs, their form re- 
sembling that of a barrel without a bottom(4). ° 
The Catiianir2, Pér. only seem to differ from Beroe by having 
much more projecting ribs united in pairs forming two species of 
wings. Their internal organization is not yet well known(5). 
The Tanirzx, Oken, appear to approximate to Callianira, but they 
are figured, on each side, with three long ciliated ribs, and two 
long ramous filaments. 6). 
The Arcinogs, Rang., have a cylindrical body, open at one ex- 
tremity and furnished at the other with two large wings, which, when 
(1) According to Messrs Audouin and Milne Edwards, there exists, in the axis 
of these animals, a cavity extending from one pole to the other, and communi- 
cating externally by means of an inferior opening, which may be considered as 
an anterior mouth. In the superior third of this cavity is contained, and, as it were, 
suspended, a sort of straight and cylindrical intestinal tube, whose exterior orifice 
is exactly at the superior pole, bearing two granular strings—the oyaries?—on each 
side. The cavity is filled with a liquid in motion, which may be seen passing into 
two lateral tubes, that are soon divided into four branches, and reach the surface 
of the body, by opening into longitudinal canals which conduct the fluid into the 
cilia that are constantly in motion, and appear to be organs of respiration. Fi- 
nally, from the lateral parts of each of these eight costal canals, arise an infinity 
of little transverse vessels or sinuses, which establish a communication between 
them, and dip into the surrounding parenchyma. 
On each side of the spheroid, and internally, are two small masses, each of 
which occupies the bottom of a cavity or cul-de-sac, and gives rise to a long con- 
- tractile filament; these two filaments issue through two circular openings, situated 
near the inferior third of the body. They are afterwards divided into numerous 
branches. 
(2) Add Beroe novem-custatus, Brug. ; Last., loc. cit., f. 5, and Encyc., XC, 2. 
The Bero¢ ovum, Fab., Groenl., 362, does not seem to differ from the pileus. 
(3) The Beroé ovatus, Brug., or Medusa infundibulum, Gm. ; Brown, Jam., XLUI, 
2, and Encyc., XC, 1;—Beroe macrostomus, Pér., Voy., pl. xxxi, f. 1;—Beroe ovata, 
capensis, punctata and constricta, Chamiss. and Eisenh., Ac. Nat. Cur., X, p> i, pl. 
Xxx and xxxi. 
N.B. The animal of Martens, Spitzb., pl. P, f. h, which is considered as identi- 
cal with that of Brown, should rather be approximated to the first subgenus. 
(4) Doliolum mediterraneum, Otto, Ac. Nat. Cur., XI, p. Il, pl. xlii, f. 4. 
(5) Callianira didiploptera, Pér.; Ann. du Mus., XV, pl. ii, f. 16. 
(6) Beroé hexagone, Brug.; Encyc. Vers, pl. 90, f. 6. 
