BEEOE FOESKAHLII. 121 



situated at the inferior extremity of the body, the eight longitudinal 

 trunks terminate in a transverse annular canal that communicates in 

 its turn with two vertical trunks much more deeply seated than the 

 preceding vessels : these lateral vessels, mounting upwards, terminate 

 in the stomachal cavity. 



(315.) The vascular apparatus above described is filled with a fluid in 

 constant circulation, in which may be perceived innumerable round 

 colourless globules. The course of the current is directed from the 

 inferior vascular ring through the eight superficial canals situated 

 beneath the ciliated ribs towards the summit of the body, whence it 

 subsequently descends in a contrary direction through the two deep- 

 seated trunks above described into the annular vessel, thus completing 

 the circulatory round. The movement of the circulating fluid is tole- 

 rably rapid ; nevertheless no traces appear of any central organ of im- 

 pulsion, neither do the vessels exhibit the slightest contractility ; in 

 some of -the larger trunks, however, the presence of cilia is distinctly per- 

 ceptible, by the agency of which the circulatory current is produced. 



(316.) From the researches of Milne -Edwards, it appears that the 

 vascular system of the Beroeform Acalephs communicates with the 

 exterior by means of emunctory canals analogous to the anal tubes 

 situated on the margin of the disk in Medusa aurita, described above. 



In Beroe ForsJcahlii, Milne-Edwards was enabled to assure himself of 

 the existence of two such outlets, situated not at the inferior margin of 

 the body, as in other Acalephs, but at its upper extremity. When this 

 portion of the animal is fully extended, it frequently occurs that a little 

 ampulla suddenly makes its appearance on one side or the other of the 

 terminal fossa, which, quickly increasing in size, exhibits in its interior 

 movements of rapid rotation ; then, suddenly opening at its summit, it 

 discharges its contents and immediately disappears, leaving no traces of 

 its excretory functions except a minute pore, which is easily distin- 

 guishable. These excretory ampulla communicate with the gastric 

 cavity that forms the central reservoir of the vascular apparatus, and 

 are evidently emunctories through which feculent matters are expelled. 



(317.) The body of the Beroes has generally been described as having 

 the form of a bag open at both ends, a mistake which is explicable 

 from the circumstance that, when the animal is not completely unfolded, 

 its superior extremity is retracted and puckered up in such a manner as 

 to give the appearance of a wide orifice placed opposite to that which 

 occupies the inferior extremity : this appearance, however, is deceptive ; 

 for if one of these Acalephs is carefully examined while swimming 

 freely in its native element, it becomes evident that the supposed upper 

 orifice is only a deep cavity the bottom of which is furnished with a 

 delicate contractile arborescent fringe, in the centre of which is situated 

 a little pyriform papilla, regarded as constituting an ocular apparatus. 



(318.) This oculiform speck, which is situated immediately in the axis 



