52 DISCOPHORiE. Part III. 



parts, or from the abortion of some of them. Ehrenberg has so fully represented 

 these variations, in the Aurelia aurita of Europe, and they are so similar with 

 those observed in our species, that I need only allude to the fact, that besides 

 the normal form, I have observed on our coast specimens with three, five, six, 

 and seven crescent^shaped bodies, and a number of indentations along the margin 

 increased correspondingly. But these deviations from the normal number are rare 

 with our species, and though Ehrenberg does not allude to their frequency in the 

 European, I should infer that they are more frequent in Aurelia aurita, than in the 

 flavidula, for the simple reason that malformations of the crescentrshaped bodies are 

 rarely met ^vith in our S25ecies. 



Whenever these parts occur in their normal number, it is at once evident that 

 the crescentrshaped bodies, which are the genital pouches, alternate with the ap- 

 pendages of the lower surface, which are the arm-like prolongations of the angles 

 of the mouth. It thus appears that the four corners of the mouth (PI. XP. Fig. 

 17, and PI. XP. Fig. 5) alternate Avith the genital pouches, though in very old 

 specimens (PI. VI. and VII.) the oral appendages exhibit a tendency towards an 

 approximation to one anothei', so that their extremity does not appear strictly in 

 the prolongation of the intervals between the sexual pouches, though their l^ase 

 occupies exactly that position. Again, of the eight prominent indentations of the 

 margin, four correspond to the centre of the sexual pouches, while four others, 

 alternating with them, are situated in the radial prolongation of the angles of the 

 mouth. This once ascertained, it is easy to aj^preciate the peculiar symmetry of 

 the whole framework of this animal, and to perceive the remarkable difference which 

 exists between the different systems of radiating tubes extending from the centre 

 to the periphery. From each corner of the mouth, and between two adjoining 

 genital pouches, arises one main radiating tube, extending straight to one of the 

 marginal indentations, without lateral ramifications, except from near its base, on 

 each side of which arises one branch which divides again and again, anastomosing 

 among themselves. Of such systems there are, normally, only four. 



The systems which correspond to the radial prolongations of the genital 2)ouches 

 are far more complicated : in the first place, the sexual pouch itself must be con- 

 sidered as a sack-like enlargement of this radiating system, and from the outer wall 

 of this sack arise the peripheric radiating tubes belonging to it, three of which 

 are simple, and extend directly to the margin without ramifications. The central 

 one extends from the middle of each genital pouch to the corresj)onding marginal 

 indentation; the outer ones, bordering each genital system, arise independently near 

 the outer angles of the genital pouches, and between these three simple tubes, arise 

 further, from the peripheric edge of the genital pouch, one or two branching radi- 

 ating tubes, the branches of which anastomose with one another. There is less 



