68 THE ACALEPHAE. <§> 64. 



§ 64. 



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

 fbrm cavity, communicating with the stomach by two orifices, situated at its 

 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 short canals which 

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

 externally. 



With Eucharis and Cydippe, these canals are diiferently 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 Beroe, 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 Beroe 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, Gerijonia and Thaumantias, there are four of these canals,^ 

 arranged in a crucial manner ; *^> and in 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 bi'anched. 



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 perhaps 

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

 directly upon the outer surface."*' 



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



very minute researches upon the aquiferous sys- 8 In Diphi/es, this canal terminates in this way 



tem of Eucharis, Cydippe and Beroe. That of by an oval dilatation, lined with cihated epithelium, 



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



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



Milne Edtuards as a cuxulatory system (Ann. organ. A similar cavity, with a coecal appendage, 



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



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



2 Will, loo. cit. Taf. n. fig. 5, 7, 8, 14, 16. ings, of the Physophorae, are really stomachs, then 

 S Milne Edwards, Ann. d. Sc. Nat. XVI. p. the cavity beneatli them, whicli has a canal 



197, PI. I. fig. 1. passing along the axis of the animal, should be 



4 Rosenthal, Zeitsch. f. Physiol. I. Hft. 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 



a Eschscholtz, loc. cit. Taf. IV. ; also Brandt, mouth by Philippi {MiUler^s Arch. 1843, p. 63, 



Mtm. de I'Aoad. d. Sc. de St. Petersbui-g, IV. 1838, Taf. V. flg. 10). According to Lesson (Duper- 



Pl. IX. X. XI. rey. Voyage, loc. cit. No. 6, fig. B.), there is be- 



G Ehrenberg, Muller''s Arch. 1834, p. 566; tween the suckers of f'e/e/ta an orifice which leads 



also, Abhandl. &c. loc. cit. p. 188, Taf. I. fig. 1, from before backward into a large branching canal. 



w. and Taf. IV. flg. 2, z. This structure, hithert-J regarded as a digestive 



