426 ACALEPHA. 



Idya, Oken — which are merely in the form of a sac, furnished with 

 ciliated ribs and open at both ends*. 



Some — DoLioLUM, Otto — are even destitute of ribs, their form re- 

 sembling that of a barrel without a bottom f. 



The CallianiR.^, Per., 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 ;{: . 



The Tanir/E, Oken, appear to approximate to Callianira, but they 

 are figured, on each side, with three long ciliated ribs, and two long 

 ramous filaments §. 



The Alcinoes, Rang., have a cylindrical body, open at one ex- 

 tremity and furnished at the other with two large Avings, which, when 

 folded over, completely envelope it. Its cylindrical portion is flanked 

 with four projecting ribs terminating in a point and marked by five 

 lines of cilia ||. 



The OcYROES, Rang., have a similar body, with four ranges of 

 cilia, but without ribs, and similar wings, each furnished at base Avith 

 two ciliated points^. 



It is also near the Beroes that Ave must place the 



Cestum, Lesiieur, 

 A very long gelatinous riband, one of Avhose margins is furnished 

 Avith a double roAV of cilia ; they are also apparent on the inferior 

 edge, but are smaller and less numerous. It is in the middle of the 

 inferior margin that Ave find the mouth, aAvide aperture opening into 

 a stomach placed transversely in the thickness of the riband, and 

 terminating by a very small anus. From the anal extremity arise 

 vessels AAdiich traverse both extremities of the riband. Tavo sacs, 

 probably ovaries, open en the sides of the mouth. Tliis animal may 

 be compared to a Callianira Avith tAVO ribs, and excessively elongated 

 Avings. Tlie only species knoAvn is the 



C. veneris, Lcsueur, Nouv. Bullet des Sc, June 1813, pi. v. 

 f. 1. Its length, or rather Avidth, exceeds five feet, and it is two 

 inches in height. It inhabits the P.Icditerranean, and is A'ery 

 difliicult to preserA'e entire**. 



The tAVO folloAving genera, Avhich were formerly joined Avith the 



* The Beroe ovatus, Brug., or Medusa infundibuhun, Gm. ; BroAvn, Jam., XLIII, 

 2, and Encyc, XC, 1 ; — Beroe macrosfomus, P^r., Voy., pi. xxxi, f. 1 ; — Beroe ovafa, 

 capensis, punctuta and coiistricUi, Cliamiss. and Eisenli., Ac. Nat. Cui-., X, p. i, pi. 

 XXX and xxxi. 



N.B. The animal of Martens, Spitzb., pi. P. f. h, which is considered as identical 

 ■with that of Brown, should rather be approximated to the first subgenus. 



f BoHoluni mediterruneum, Otto, Ac. Nat. Cur., XI, p. II, pi. xlii, f. 4. 



X CuUianira didiiiloptera, Per.: Ann. du Mus., XV, pi. ii, f. IC. 



§ Beroe hexagone, Brug. ; Encyc. Vers, pi. 90, f. 6. 



II Alcince veniiiada/a. Rang., Mem. de la Soc. d'Hist. Nat. de Par., IV. xix 

 1,2. 



^[ Ocyroe maculata, Id. Ib.,xx, 1, 2; — Oo. fusca. lb. 3: — Oc. crysiuUina, lb., 4. 



The Calliunira helcroptera, Chamiss. and Eisenh., Ac. Nat. Cur., X, p. II, pi. 

 xxxi, f, 3, will probably form another subgenus, 



** The Lcmnisque, Q,uoy aud Gaym., Zool. de Freycin., pi. SG, f. 1, is pei'baps a 

 fragment of a Cestum. 



