208 NAXOMIA CARA. 



polyp ; as has already been shown by Sars in Agalmopsis, the sexes are 

 distinct, so that we have whole communities, the sexual Medusaj of 

 Avliich are either males or females. There is no great difference be- 

 tween the ajjpearance of the male and female Meduste ; they do not 

 (as is the case in Agalmopsis, according to Sars) separate from the com- 

 munity, and lead an independent existence ; they wither on the stem, 

 after having discharged their contents. The Medusa} form bunches, 

 the single Medusaj of which are directly attached to the main axis ; 

 they are somewhat pointed in outline, with four tolerably well defined 

 Fig. 346. chymiferous tubes, resembling quite closely the sessile Me- 

 dustu of such Tubularians as Tuhularla Cfmthoinjl. 



From the observations of Gegenbaur, there can be no doubt 

 tliat many of the Siphonophores are, like Nanomia, developed 

 directly from the egg, and that the embryo which comes from 

 the egg is one which is identical with those found floating 

 about in such unmense numbers during the early part of 

 June, and which are figured in Fig. 346, consisting of a single closed 

 polyp and of an oil-float, separated by a partition, as in the adult (Fig. 

 331); this simple polyp is to be the axis of the future community. 

 But these young Nanomia? (Fig. 346) do not all arise from eggs, and 

 pass directly into an embryo like Fig. 346 ; we have a second kind 

 of development, that of budding. In Fig. 338 there is represented on 

 the top an appendage resembling somewhat a polyp without an open- 

 ing, having neither tentacle nor protecting scale. A bubble of oil is 

 collecting at the proximal extremity ; as this bubljle increases in size, 

 the neck which connects the polyp with the main axis gradually 

 becomes narrower and narrower, until the connection is finally cut, 

 and we have a bud resembling in every respect Fig. 346, whicli has 

 separated from the main community. By keeping in conflnement. 

 Fig. 347 entirely isolated, an adult Nanomia having many of these 



Inuls along the main axis, I have found after a few days 

 a larsje number of these buds liberated, which had as- 

 sumed the shape and structure of Fig. 346, and had 

 grown to be similar in every respect to the embryos I 

 was fishing from the sea at the same tune. From this 

 I should infer that we have two broods of adults, those 

 whicli are ibund in the fall, and which lay eggs in Octo- 

 ber and November, and those which are probably formed by budding 

 from the older ones during the summer and winter ; the embryos found 

 in early summer ma}- have come from the eggs of either of these. 



Tlie 3'oung embryos (Fig. 346) readily keep alive in confinement, 

 and it is a comparatively easy thing to trace the successive stages of a 



Fi^. 34ij. Vminjjist Xanomia t'otiiiil swiimuiiig ou surfai-c. 

 Y'l-'. 347. Somcwliat more advancLil. 



