256 BULLETIN OF THE 



of an otocyst. They represent approximately those lappets which in the 

 genus Aurelia project far beyond the bell margin. 



Between each pair of crescent-shaped bodies there are three or four pointed 

 serrations (v /) which represent in position the tentacles. The bell rim has a 

 wavy crenate outline, slightly indented between the marginal serrations, and 

 deeply incised between the crescentic bodies which have been mentioned above. 

 The otocysts are found in the angle of these deeper incisions. 



The anatomy of the oral region (fig. 11) of Cassiopea is in certain respects 

 peculiar. When the jelly-fish is seen from this side, which is uppermost in the 

 natural position of the medusa, a confused mass of bodies of all sizes covers it 

 and conceals completely the bell itself. These bodies give to the Cassiopea, 

 when seen from a distance, a remote likeness to a marine alga. If, however, 

 the innumerable bodies which cover the oral pole of the medusa be pushed 

 apart (tig. 11) so that their attachment can be seen, it will be found that they 

 arise from branches which primarily originate from eight gelatinous arms (oral 

 arms, rf), which are themselves prolongations from a centrally placed projection 

 (•• Mundscheibe," t) from the oral surface of the bell. 



In the middle of the lower floor of Cassiopea there rises a cylindrical body, 

 Mundscheibe (i), of gelatinous consistency, which gives origin to the eight oral 

 arms (d) of the stomach. It is an octagonal body, and is without opening on 

 the upper surface. There is no single central mouth in Cassiopea. and no 

 centrally placed orifice * into the cavity of this cylinder. The only external 

 openings which are to be found are four orifices (o) on the sides of the body of 

 the Mundscheibe, 90° apart. These openings lie in the intervals between 

 the four pairs of branching oral tentacles, and are the sexual orifices. They 

 communicate directly between the cavity of the ovaries which lie in that of 

 the oral cylinder (PI. III. fig. 3, s o) and the surrounding water. 



Eight oral arms (</) are found branching in pairs from the sides of the 

 oral cylinder, Mundscheibe (<). These appendages form the most important 

 structures in the oral region of the Cassiopea, and bear organs which, as is 

 probablv the case in all Ehizostomata', represent the mouths of other genera 

 of I liscophora. Each oral arm extends at right angles to the sides of the oral 

 cylinder, and parallel to the lower surface of the bell. It is irregularly 

 branched (IT. I. figs. 17, 19), and has solid walls of a gelatinous character. 

 The outer surfaces (fig. 17) mined to the bell and the sides are smooth, while 

 tin- upper surface (fig. 10) is covered with innumerable ilask-shaped structures 

 of different shapes and sizes. A Bystera of vessels (gv) runs along the upper 



part of the oral tentacle just below the surface, communicating with the lla-k- 



shaped bodies and a centrally placed chymiferous cavity. There an- two kinds 

 of appendages found on the upper surface of tie- oral tentacles. Indiscrimi- 

 nately ovn- tin- whole surface, and at the angle of bifurcation of -mailer 

 branches from the oral arm-, we find ovoid bodies, " Kolbenformige Blasen" (/<)< 



* L. Agassi/, "//. <•;/., p. 1 17, mentions a central month opening in a young Poly- 

 clonia. 



