106 DISCOPHOR^. Pakt III. 



our beaches, in the latter part of the month of September, in which the eggs still 

 remain between the folds of the actinostome, in such numbers as to be readily dis- 

 tinguishable by the peculiar, yellowish orange tint, Avhich they impart to the places 

 where they are accumulated in greatest quantity. These genital pouches, however, 

 are so delicate that they are frequently found torn open, when the eggs necessarily 

 escape at once into the water. Whether such eggs undergo their develoi)raent or 

 not, must depend upon the stage of growth they have reached before leaving the 

 ovarian lobes. 



The connection of the actinostome with the other parts of the lower floor 

 described above, has already been alluded to ; but this apparatus is far more com- 

 plicated than in Aurelia, and requires a special description to be fully understood. 

 Within the concentric folds of the lower floor, its actinal prolongation towards the 

 central oral aperture presents marked differences. In four directions, in the actinal 

 prolongation of the ambulacra, this floor is thickened, to form the pUlars which 

 support the whole oral apparatus with its appendages; while the intervening spaces, 

 alternating with these pillars, are occupied by the thin-walled genital pouches, as 

 seen in PI. IV. Fig. 2, and PI. V^ Fig. 15, and also in Fig. 14, in which these 

 same parts are shown in a ^^rofile .section, exhibiting two of the j^illars of the 

 actinostome from the inside, in their connection with the concentric folds and with 

 the genital pouches. Each i:)illar arises with two branches (PL IV. Fig. 2, i i) 

 converging downwards to a point Avhich corresponds to a corner of the quadran- 

 gular mouth ; and the oral apparatus is suspended to four such pillars, placed in 

 the radial prolongation of the four ambulacra. As in Aurelia, the actinostome 

 consists of four so-called arms, as shown in PL V*. Fig. 16, l)ut these arms are not, 

 as in that genu.s, massive prolongations of the lower floor, thickest around the oral 

 aperture and gradually tapering to a thin extremity ; they form, on the contrary, 

 thin, broad, flowing curtains, hanging from the two sides of a somewhat thicker axis 

 or peduncle, radiating from the corners of the mouth to the periphery of the four 

 great curtains. Each of these masses of flowing folds is, as it were, gathered up 

 round that peduncle, near its base (PL IV. Fig. 2, 5, and PL V^ Fig. 15, 5). The 

 flowing curtains (tZ J), properly correspond to the fringed mai'gin of the Aurelia; 

 while the stronger medial fokls (PL IV. Fig. 1, s, and PL V^ Fig. 16, s s s s\ 

 answer to the back of the arms in Aurelia. At the junction of the pillars with 

 the medial folds of the four curtains, there is developed, in the thickness of the 

 prolongation of that part of the lower floor which forms the genital pouches, a 

 thick cylindrical beam (-3), which connects the four pillars together, and while 

 keeping them from spreading, gives the oral aperture a quadrangular form. The 

 flowing curtains themselves extend also along the margin of these beams, as seen 

 in PL V\ Fig. 14, i^, and Fig. 15, d}\ so that the entrance to the main central 



