258 BULLETIN OF THE 



Through them the food material collected from the mouths on the upper side 

 of the oral arms by a system of chyiniferous vessels (PI. I., g v), is poured into 

 the stomach cavity occupying the centre of the disk. 



The chymiferous vessels of the bell of Polyclonia have been w^ell described by 

 L. Agassiz. My observations agree with his and those of Haeckel of Cassiopea 

 omata. I have nothing to add to the account which they give. 



In regard to the marginal sense bodies, my observations are a little more 

 complete than any yet recorded. The few points which can be added to our 

 knowledge of these organs appertain only to their gross anatomy. 



In external form the marginal sense bodies (PI. I. figs. 12-16) of Cassiopea 

 resemble those of Amelia and Cyanea. There are sixteen of these structures, 

 each of which lies at the extremity of a radius passing through one of the pear- 

 shaped racV d stripes (ef) which have been described in the bell. They are set 

 in deep incisions in the bell margin, and are flanked on either side by the 

 ocular lappets (o /). A " hood " (A) protects the sense organ on its aboral side. 

 This structure resembles that of Cyanea, and is simply stretched from one 

 ocular lappet to another. There is no aboral " Sinnespolster." The outer 

 " Riechgriibschen " is wanting. There are no finger-like lajipets, as in Aurelia 

 and only diminutive oral " sense curtains," as in Cyanea. The inner " Riech- 

 griibschen " are very small. 



The otocyst is mounted on a short peduncle, and is more spherical in shape 

 than the same organ in most other Discophora. It seems to tit into the end of 

 its style as an acorn into its cup, and not to be united to it liy an elbow- 

 joint as in Aurdia and Cyanea. The otoliths have a rhomboidal form and a 

 yellow color. 



An ocellus (oc), or cluster of pigment spots, can easily be seen through the 

 walls of the hood. It is situated on the aboral side of the otocyst, near the 

 enlargement of the style into the cup-shaped end into which the otocyst fits. 

 In normal specimens (fig. 12) there is but a single ocellus to each otocyst, yet 

 in many cases we find a style bearing an otocyst with two ocelli (fig. 16). In 

 several instances, also, a bifurcated style supporting two otocysts (figs. 14, 15) 

 as well as two ocelli was observed. Variations in the number of otocysts 

 about the margin of the bell of Cassiopea are very common.* 



Little is known of the development of Cassiop>ea. The youngest specimens 

 taken were about an inch in diameter, and had already assumed the character- 

 istic posture (7 «) of the adult. In the youngest, however, the central mouth, 

 spoken of by L. Agassiz in the young PolydoJiia, was not observed. The larval 

 Cassiopea (fig. 8) differs but little except in size from the adult as far as the oral 

 region is concerned. The "sucker frills " (Saugkrausen) are less abundant and 

 the large flask-shaped bodies fewer in number in the young medusa than in the 

 adult. The coloration of the aboral side of the bell diff'ers markedly from that 

 of the adult. The disposition of color is as follows : — 



* Polyclonia, which lias twelve otocysts according to L. Agassiz, may be an abnor- 

 mal Cassiopea in which the number of sense bodies is normally sixteen. 



