68 THE ACALEPHAE. § 64. 



§ 64. 



With the Ctenophora, this respiratory system consists of an infundibuli- 

 form cavity, communicating with the stomach by two orifices, situated at ita 

 base and surrounded by sphincters. 



Numerous aquiferous canals pass out of this cavity, traverse the body in 

 a longitudinal direction, and finally anastomose with an annular vessel 

 surrounding the mouth ; but, beside these, there are two shoi-t canals which 

 pass directly to the posterior extremity of the body, where they open 

 externally. 



With Eucharis and Cydippe, these canals are difierently distributed ; 

 thus, two go to the tentacles, two to the sides of the stomach, and four to 

 the sides of the body. The same is true with Bero'e, excepting that those 

 to the tentacles are wanting. The lateral canals divide, at a short distance 

 from the cavity, into as many branches as there are sides. With Cydippe, 

 the excretory canals are simple ; with Eucharis they are provided with 

 vibratile lamellae, and with Bero'e with branching appendages. <'' 



With the Discophora, numerous aquiferous canals pass from the stomach 

 or its appendages, traverse the disc in a radiating manner, sometimes bifur- 

 cating, and terminate at the borders of the disc in an annular vessel which 

 opens externally by numerous orifices. 



In Cytaeis, Geryonia and Thaumantias, there are four of these canals, 

 arranged in a crucial manner;*-* and m Aequorea there are seventy-four 

 disposed in a ray -like way."^' 



In Medusa aurita, there pass from the four folds of the stomach six- 

 teen of these canals, eight of which are simple, and eight bifurcating 

 numerously before reaching the marginal vessel of the disc.''" With Sthe- 

 nonia and Aurelia^^^ they are very numerous and widely branched. 



With Medusa aurita, the terminal openings of the annular vessel are 

 eight, and regularly alternate with the organs of hearing there situated.''"' 

 But in Cephea these openings are said to be directly beneath these last- 

 named organs,"^' 



With the Siphonophora, an aqueous system has not yet been well made 

 out. There is, however, with some, an elongated cavity which is pei'hap» 

 respiratory, and which, in some species, opens into the stomach, and in others 

 directly upon the outer surface."*' 



1 Will (Horaj tergest. p. 30, Taf. I.) has made 7 fVill, loc. cit. p. 60. 

 Tery minute researches upon the aquiferous sys- ** In Dipht/es, tliis canal terminates in this way 

 tem of Eucharis, Cydippe and Beroi. That of by an oval dilatation, lined with ciliated epitlielium, 

 Beroe ovatus, Forskalii, and of Lesueuria vi- and has perhaps properly been regarded by fVill 

 trta, has been carefully described and figured by (loc. cit. p. 78, Taf. II. fig. 22, a.) as a respiratory 

 Milne Edwards as a circulatory system (.4.nn. organ. A similar cavity, with a coecal appendage, 

 d. Sc. Nat. XIII. p. 320 ; XVI. p. 203, 213, 1*1. is found in Ersaea {Will, loc. cit. p. 81, Taf. II. 

 III.-VI.). fig. 27-31, d. e.). If the arms provided with open- 

 ly Will, loo. cit. Taf. II. fig. 5, 7, 8, 14, 16. mgs, of the fAyso/)Aoraf, are really stomachs, then 

 8 Milne Edwards, Ann. d. Sc. Nat. XVI. p. the cavity beneath them, which has a canal 

 197, PI. I. fig. 1. ])assing along the a.\is of the animal, should he 

 i Rosenthal, Zeitsch. f. Physiol. I. lift. 2, Taf. taken as belonging to the aquiferous system, for it 

 XI. ", also, Ehrenberg, Abhandl. d. Berl. Akad. receives water by an opening at the base of the 

 1835, Taf. I. bis. III. anus. This same opening has been taken for a 



5 Eschscholtz, loc. cit. Taf. IV. ; also Brandt, mouth by Philippi (Muller's Arch. 1843, p. 63, 

 Mtm. de I'Acad. d. Sc. de St. Petersburg, IV. 1838, Taf. V. fig. 10). Ac^ordiuK to Lesson (JJuper 

 PI. IX. X. XI. rey. Voyage, loc. cit. No. 6, fig. B.), there is 1«- 



6 Ehrenberp, Müller's Arch. 1834, p. 566 ; tween the suckers of yelella an orifice which leads 

 alio, Abhandl. &c. loc. cit. p. 188, Taf. I. fig. 1, from iK-fore backward into a large branching canal. 

 W. and Taf. IV. fig. 2, z. This structure, hithert<) regarded as a digestiv« 



