BAITAMA MEDUS.^. 5 



Gonionemiis, Cubaia, Valleiitinia, Oliudioides and Olindias are closely re- 

 lated geuera, wliicli may be }>T()uped into one family, the Oliudiada'.* The 

 marginal (velar) lentacles of Cuhai.i ;uid Olindias are secondary and arise 

 quite late in ontojicny. The dlstinguisliinji feature of the Olindiadiv is the 

 development of a jiad-like cluster of modified nematocyst cells upon the abo- 

 ral side, near the distal extremity, of eacii and nil of (lie primirive tentacles. 

 These pad-like expansions may serve as adhesive disks or organs of tempo- 

 rary attachment. 



A study was also made of the phenomenon of asexual budding in medu- 

 sae. One of the most interesting examples is afforded by EuchcUotu para- 

 doxica, which is the only Leptomedusa known that produces an asexual 

 generation of medusa' by a direct process of budding. These daughter me- 

 dusa? are derived from both entoderm and ectoderm of the gonad of the pa- 

 rent (Fig. 65, Plate VII). 



We have, therefore, a graded series of phenomena in the asexual produc- 

 tion of medusa buds by hydromedusiip. In forms where the ectoderm and en- 

 toderm are both thin-layered and of ab mt equal thickness, such as in the *?«;•- 

 strtrfrte and y-J. ;)o/Yf(/oj"i>«, both entoderm and ectoderm take an equal share in 

 the formation of the bud. In forms such as Rathkea octopuncUita and 

 Ijizzia Clapereidei, according to Chun, 1895, a different condition is observed, 

 for the medusa buds are formed entirely within the ectoderm of the parent, 

 although the gastro-vascular cavity of the bud finally ac(iuires a connection 

 with that of the parent; the entoderm of tlu' bud becoming continuous with 

 that of the parent manid)rium. 



In Bongainvillia niobe from the Bahamas, however, the (>ctoderm is very 

 thick, and the budding medusiP are developed within it alone; the entoderm 

 remaining inert and passive during the growth of the bud, and no connection 

 ever being established between the gastro-vascular cavities of the bud and the 

 parent. (See Figs. 15-15c, Plate II.) This result may be regarded as due 

 to a gradual process favored by the thickness of the ectoderm, which pre- 

 vented the deep-lying entoderm from taking an equal share in tJie fdrmation 

 of the bud, until finally, as in P.. niol)e, it renmins i»assive throughout the pe- 

 riod of the formation of llic bud. iledusa' produced from ('(■((idcrm alone 

 may, therefore, be pliylogeneticaljy homnlogous with mcdus;!' prndu(('(l bv 



* Goto, S. 1903 : ^lark Anniversary Volume. 



