BAHAMA MEDUSiE. 5 



Gonionemus, Cubaia, Vallentinia, Olindioides and Olindias are closely re- 

 lated genera, which may be grouped into one family, the Olindiadse.* The 

 marginal (velar) tentacles of Cubaia and Olindias are secondary and arise 

 quite late in ontogeny. The distinguishing feature of the Olindiadic is the 

 development of a pad-like cluster of modified nematocj'st cells upon the abo- 

 ral side, near the distal extremity, of each and all of the primitive 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 Eucheilota para- 

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

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

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

 rent (Pig. 65, Plate VII). 



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

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

 toderm are both thin-layered and of about equal thickness, such as in the 8ar- 

 siadae and E. paradoxica, both entoderm and ectoderm take an equal share in 

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

 Lizzia 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 acquires a connection 

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

 that of the parent manubrium. 



In Bougainvillia niobe from the Bahamas, however, the ectoderm is very 

 thick, and the budding medusae 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 the formation 

 of the bud, until finally, as in B. niobe, it remains passive throughout the pe- 

 riod of the formation of the bud. Medusae produced from ectoderm alone 

 may, therefore, be phylogenetically homologous with medusae produced bv 



* Gcito, S. 1903 ; Mark Anniversary Volume. 



