MUSEUM OF COMPARATIVE ZOOLOGY. 257 



which, when extended, assume a flask-like form. The structures have walls 

 of a greenish color with darker interiors, and communicate with the chymifer- 

 ous tubes of the oral tentacles. They have no opening at their unattached 

 end, and are simply closed sacs for the reception of fluid. The function of 

 these bodies is unknown. 



A second* Iciud of polyp-like bodies (p') is scattered over the upper suri'ace 

 of the oral tentacles. These are more numerous and smaller tlian the first. 

 They are the true mouths of the CassiojJea. They resemble frills, between 

 which there are slits surrounded by a circlet or row of minute tentacles. It 

 is in fact as if we had the whole upper surface of the oral tentacle covered 

 with small fresh-water hydraj, with mouth-openings very much elongated 

 laterally', and around which the circumoral tentacles are very numerous. The 

 central opening, or mouth, may be a circular orifice or an elongated slit. 

 Whatever its form may be, the circlet of tentacles about it is always arranged 

 in a single series. These sacs or sucking mouths communicate with the same 

 system of vessels ((/ v) as the flask-shaped bodies (p) mentioned above. They 

 are the mouths of the jelly-fish. 



Within the Mundscheibe, or oral cylinder, there is a thin disk-shaped cav- 

 ity (PI. III. fig. 3), which may be called the stomach. Its floor is formed by 

 the up[)er surface of the bell, and its roof by the upper wall of the Mund- 

 scheibe. The most prominent structures in the stomach are the four sexual 

 organs, or, more accurately speaking, the four sexual sacs, since the sexual 

 organs themselves (o) are separated from the stomach by a thin gelatinous 

 wall. The ova cannot pass into the stomach, but are dro[)ped in these sacs, 

 and from them into the water through the ibur openings (so) on the side of 

 the oral disk. It will be noticed then that the ovarian openings do not lead 

 into the chymiferous cavity, but into four sexual sacs which lie in the stomach. 

 Morphologically, as has been suggested, the sexual sacs are invaginations 

 of the outer surface of the Mundscheibe at the point where the sexual open- 

 ings (so) lie, and their cavities are wholly independent of that of the stomach. 

 There are four sexual glands hanging to the walls of the sexual sacs, which 

 are fastened to the oral disk or roof of the stomach on a V-shaped line, each 

 gland filling a quadrant of the circle in which it is found. On the roof of the 

 stomach between the lines of attachment of the sexual sacs, four grooves (g) 

 are left, which cross each other at the centre at right angles. These grooves 

 are simjily spaces left between the lines of attachment of the sexual sacs. 

 Near its peripheral end each groove deepens, and at the extremity sinks into 

 an opening (6),f which communicates with the system of chymiferous ves- 

 sels (PI. I., </i') in the upper walls of the mouth arms. The openings (h) 

 into the stomach alternate in the oral disk with the sexual orifices (s o). 



* One or two large white flask-shaped bodies were also observed. Compare 

 Haeckel, op. cit., p. 571. 



t These openings were discovered by L. Agassiz in Polydonia, op. cit. Haeckel, 

 op. cit., pp. 566-573, does not mention them. They are also omitted in his figures 

 of C. oniata, op. cit., XXX VII. 6. 



Vol. IX. — NO. 7. 17 



