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Show ACALEPllA. 376 p 6ron-for little foss- FovEoLIA, ( ) d with laminre, and others-:- ference of the umbella 1 • covere 1 d ound the circum ulre, which are p ace. r d r the name of We might also umte un e PELAGIA, into a peduncle or is di- . h' h the mouth is prolonged Those m w lC . h . ded into arms(2). no lateral cavities, but m a muc VI In all these subgenera there a: with a simple mouth, V:e find, in greater n umber of thesbe Mllae dfuosu r organs formed of a plaitebd mem-the t h.IC kness of the u.m e ' fill d ith an opaque su stance, 5 are e w . b which at certam season. Th y are usually placed mas rane, b ovaries. e ·d f th d which appear to e . I! • surface or on the Sl es o e an . the m1er1or ' . . ) k ft ny cavities openmg on sly (in my opimon ta en or ma . h been erroneou . h (S) d·cle and which ave ti'mes entangled m t em . pe I ' 1 · als are some f · mout hs, because litt e ammor gans f . tion(4) but that unction 0 resp1ra ' T Others consider them a.s the ed es of the umbella. he ten- . most probably exercised by .g f the umbella or round the lS • t d on the margm o f th tacula, whether sltua e d' t the species, but the age o e mouth, vary, not only accor mg o animat(s). of We will unite, under the name CYAN..IEA, Cuv. l th and four lateral ovaries. All the Medusre with a ce~traL~~un., Zoot. Dan. ;LXXVI, and C aurita; Medusa aurtta, ., 1 di' sseminated species, ac- . f h st common y r LXVII. One o t e mo th whole circumference o . f long arms; e d quiring With age our. . • reddish branching vessels procee its umbella is finely c~hat~~umference. In the from the sto:mach to Its cir C the edges are furnished C. chrysaora; Med. chrysaora, b;:~n lines or spots arranged with long tentacula. or fulvous or . • k XXXUI, C; Encyc:, XCV, 1' 2 '· -Medu8(!. per/a, 1) Medusa mollunna, Fors ., th~ genus MELICERTJ:, P~ron. V x Terres Aust., XXXI, 2; the CALLillROE . ra P~ron oy. au (2) Pelagta panopy ' d 1 'be united to it. . . ortion of and Ev .&.oon.A, Per., shoul a so d M"ller induced Peron to dlVlde a p (3) This opinion of Baster a.n u these Medusce into Monostoma. a.nll Polystoma. ( 4) Eisenh., on the RhisostQffla, &c. (S) See Mull., Zool. Dan., II, P· Sl. SIMPLICIA. 377 in radii on its convexity. This species also is extremely com-mon, and varies greatly as to the spots( 1 ). . We have given the general name of RarzosTOMA 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. RHIZOSTOMA, proper, Includes those whfch 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 Rhizoatome bleu, Cuv., Journ. de -Phys., XLIX, p. 436; Reaum., Ac. des Sc., 1710, pl. XI, f. 2T, 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 of vessels extends round the umbella in the thickness of its margin(2). ( 1) Most of the Chrysaora of Peron are mere varieties of this species.-Add .O.urelia crenata, Chamiss., and Eisenh., Ac. Nat. Cur., X., p. J, pl. xxix. Besides the Chrysaora, we refer to this genus the AuRELIA, CYANEA, ODELIA. and OcEuu. of Peron: we also include in it Medusa hemisplterica, MUll., VII, 5; Encyc., 93, 8, 11;-M. cymbaloide8, Slaber., Encyc., lb., 2-4, if we may trust to the characters of such small individuals;-Oallirlwe basteriana, Per.; Baster, Op. Subs., II, v, 2, 3; Encyc., XCIV, 4, 5;-the Oyanee bleu, Per.; Diquemare, Journ. de Phys., 1784, Dec. I;-the species or varieties figured, but rudely, by Borlasse, Nat. Hist. of Cornw., pl. xxv, f. 7-12, which are referable to our Cbrysaora, and to which should be approximated the Mea. ltyaocella, Gm. ;-M. tyrrhena, Gm.,&c. (2) It is the Pulmo marinua, Mathiol., Aldrov., Zooph., lib., IV, p. 575, the Medusa pul17W, Glb., Macri, Polm. Mar., I, B; Borlasse, XXV, 15. See Eisenh., Ac. Nat. Cur., X, part II, p. 377. The Potta marina, Aldrov., Ib., p. 576, is perhaps another species. I suspect that the EPRIRA, Per.,-Medusa simplex, Pennant; Borlasse, Cornw., XXV, 13, 14-is merely a Rhizostoma depl'ived of its pedicle. The MedUBa pileata, Forsk., of which Peron makes an Oceania, has the ramous pedicle of Rhizostoma proper, but enclosed under a campanulate umbella, furnished at the margin with tentacula. VoL. IV.-2 X |