SIMPLICIA. 493 
Others consider them as organs of respiration *, but that function 
is most probably exercised by the edges of the umbella, The ten- 
tacula, whether situated on the margin of the umbella or round the 
mouth, vary,not only according to the species, but the age of the 
animal +. 
We will unite, under the name of 
Cyanma, Cuv., 
All the Medusze with a central mouth and four lateral ovaries. 
C. aurita; Medusa aurita, L.; Miil., Zool. Dan. LX XVI, and 
LXVII. One of the most commonly disseminated species, ac- 
quiring with age four long arms; the whole circumference of 
its umbhella is finely ciliated; reddish branching vessels proceed 
from the stomach to its circumference. In the 
C. chrysaora ; Med. chrysaora, Cuv., the edges are furnished 
with long tentacula or fulvous or brown lines or spots arranged 
in radii on its convexity. This species also is extremely com- 
mon, and varies greatly as to the spots {. 
We have given the general name of Ruizosroma to that portion of 
the great genus Medusa which comprises species that have no mouth 
opening in the centre, and that appear to live by the suction exercised 
by their pedicles or tentacula. ‘They have four or more ovaries. 
RAIZOSTOMA, proper, 
Includes those which are furnished with a central pedicle more or 
less ramified according to the species. 
The vessels arising from the small ramifications of the pedicles 
unite in a cavity of its base, whence branches proceed to all parts of 
the umbella. 
The most common species is the Riizostome bleu, Cuv., Journ, 
de Phys., XLIX, p. 436; Reaum., Ac. des Sc., 1710, pl. XI, f, 
27, 28. It is found along the French coast at low water, and its 
umbella is sometimes almost two feet in width. Its pedicle is 
divided into four pairs of arms almost infinitely forked and 
dentated, each one being furnished at base with two auricles 
that are also dentated; a fine network cf vessels extends round 
the umbella in the thickness of its margin §. 
According to the observations of Messrs. Audouin and Milne 
Edwards, these Medusz live in society, or at least are always 
* Eisenh., on the Rhisostoma, &c. 
+ See Mull., Zool. Dan., IJ, p. 51. ° 
+ Most of the Chrysaora of Péron are mere varieties of this species—Add Aurelia 
crenata, Chamiss., and Eisenh,. Ac. Nat. Cur., Y., p. I, pl. xxix. 
Besides the Chrysaora, we refer to this genus the AURELIA, CyANEA, OBBLIA 
and CceAnia of Péron: we also include in it Medusa hemispherica, Miull., VII. 5; 
Encyc., 93, 8, 11 ;— M. cymbaloides, Slaber., Encyc., Ib., 2—4, if we may trust to 
the characters of such small individuals ;—Callirhoe basteriana, Pér.; Baster, Op. 
Subs., TL v, 2,3; Enecye., XCIV, 4, 5 ;—the Cyunée bleu, Pér.; Diquemare, Journ. 
de Phys., 1784, Dec. 1;—the species or varieties figured, but rudely, by Borlasse, 
Nat. His. of Cornw., pl. xxv, f. 7—12, which are referable to our Chrysaora, end to 
which should be approximated the Med. hysocella,, Gm. ;— M. tyrrhena, Gm., &c. 
§ It is the Pulmo marinus, Mathiol., Aldroy., Zooph., lib. IV, p. 575, the Medusa 
