256 BULLETIN OF THE 



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

 genus Aureiia project far beyond the bell margin. 



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

 serrations (« I) 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 wliich have been mentioned above. 

 The otocysts are fo\ind in the angle of these deeper incisions. 



The anatomy of the oral region (tig. 11) of CassiojJea 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, d), 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 (t), of gelatinous consistency, which gives origin to the eiglit oral 

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

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

 centrall}' placed orifice * into the cavity of this cylinder. The only external 

 openings which are to be found are four orifices (o) t)n 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 (PL 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 (t). These appendages f(jrm the most important 

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

 probably the case in all Rhizostomata', represent the mouths of other genera 

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

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

 the upper surface (fig. 19) is covered with innumerable flask-shaped structures 

 of different shapes and sizes. A system of vessels (^ v) runs along the upper 

 part of the oral tentacle just below the surface, communicating with tlie flask- 

 shajied bodies and a centrally placed chymiferous cavity. There are two kinds 

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

 nately over the whole surface, and at the angle of bifurcation of smaller 

 branches from the oral arms, we find ovoid bodies, " Kolbeniormige Blasen" (p), 



* L. Agassiz, op. cit., p. 147, mentions a central mouth opening in a young Poly- 

 clonia. 



