F. S. CONANT ON THE CUBOMEDUS^. 25 



formed as in the Chirodropidae. Furthermore, as happens in the latter 

 family but does not in the Chary bdeid;e, the marginal pockets extend 

 into the velarium. From each of the larger marginal pockets are given 

 off two velar canals, while each of the smaller gives rise to but one short 

 one (Fig. 18). Fig. 30 represents one of the last sections of a Tripedalia 

 cut transversely, in which nothing but the pedalia and the velarium 

 appear, and in it are shown the velar canals (i>c), which come from the 

 larger marginal pockets. The velarium appears in four segments because 

 it is drawn upwards in the four perradii by the frenula (see Fig. 20). 

 That the canals from the smaller pockets do not appear in the section is 

 due to their shortness and to the fact that they are pulled upwards above 

 the level of the sections by the frenula, together with that portion of the 

 velarium. 



The smaller velar canals, a pair in each perradius, seem to have in 

 the males some function in connection with the storing of matured sper- 

 matozoa. In specimens with ripe testes they are very often found 

 crowded to distension with spermatozoa, while the other velar canals 

 may or may not contain them, and generally do not. The epithelium 

 lining them is, like that of the others, composed of columnar cells higher 

 on the wall turned toward the bell cavity than on that turned towards 

 the exterior, but otherwise not specially differentiated. I searched in 

 vain for any trace of opening by which the spermatozoa might gain the 

 exterior. Fig. 29 shows another point which may be mentioned in 

 passing, namely, that the canal of each of the three tentacles opens 

 into the peripheral gastro-vascular system independently. The central 

 tentacle of each group is the homologue of the single tentacle of Chary bdea, 

 and is formed in Tripedalia before the two lateral tentacles appear. 

 Its communication with the peripheral pocket system is higher up than 

 the openings of the lateral tentacles, so that in the section drawn the 

 latter are just beginning to be indicated (cf). 



It remains only to speak of the i-eproductive organs of Tripedalia. 

 The sexes are separate in this form also, and ovaries and testes have the 

 same structure as is found in other Cubomedusas. The development of 

 floating masses of cells in the females, however, is a feature which, so far 

 as I know, has not been observed before. These masses, of which a 

 small one is represented in section by Fig. 71, are apparently developed 

 along with the eggs, and repeat the structure of the ovary to all intents 

 the same as if they were various-sized fragments of it broken loose. 

 They consist mostly of high, columnar epithelial cells surrounding a few 

 4 



