PHYSALIA. lOr) 



development. They arc — 1, polypites ; 2, tentacles; 3, hydrocysts; 4, andropliores ; 

 5, medusiform bodies, probably gynophores.' 



1. In their youngest condition (fig. 9) the polypites are pyriform processes of the 

 ectoderm and endodcrm (the latter ciliated internally) about .ioth of an inch in diameter. 

 From these rudiments a regular series of gradations could be traced up to elongated sacs 

 about one fortieth of an inch long, and r,^th of an inch wide, with rather pointed apices, 

 about which more especially, thread-cells were accumulated (fig. 10). The endoderm, ciliated 

 on its inner surface, sometimes presented an appearance of longitudinal fibrillation, and 

 a distinct interval, or, at any rate, a clear space, was visible between the endoderm and 

 ectoderm. Towards the proximal end, the transverse folds and villi of the latter had begun 

 to make their appearance. The villi are at first papillary, obtuse eminences, without any trace 

 of an internal cavity. As they become larger, clear vacuolar spaces appear in their interior, 

 so that they resemble the villi of the CalycoplioridcE, and dark pigment granules are deposited 

 in their apices. In polypites of larger dimensions, the folds and villi were fully developed, 

 but their distal extremities were still closed. Eventually, these open and the polypites are 

 complete. 



2. The rudiments of the tentacles (fig. 1 1 h) are, in the youngest state, hardly distin- 

 guishable from those of the polypites. The first formed part is the sac, and from the side of 

 the base of this, the tentacle buds out as a cylindrical process, one of whose walls eventually 

 thickens and becomes sacculated in the way described above. 



Many of the protuberances of the hydrosoma are covered with nothing but these 

 polypites and tentacles, but others, distinguishable even by the naked eye by their rounded, 

 velvetty appearance, exhibit only one or two small polypites arising from the midst of a 

 mass of branched, tubular processes of the hydrosoma (gonoblastidia), to which the three 

 remaining kinds of appendages are attached. 



3. The hydrocysts (fig. 13) I find described in my notes as "young stomachs," or 

 polypites, which, indeed, they resembled in every respect, save being open at the extremity. 

 They were usually placed at the extremities of the branches of the gonoblastidia. 



4. The gynophores (fig. 15) seemed also to be very generally situated towards the end of 

 a branch, though this appearance may possibly be due to their long pedicles. They first 

 appeared as rounded papilla;, about y^th of an inch in length, and having the endoderm 

 at their apex much thickened, so that it projects into the cavity of the papilla (fig. 15 a). 



The series of changes from this condition to that of the fully formed medusiform bud 

 (fig. 15 e), is quite similar to that passed through by the nectocalyces of other Phi/sophorida, 

 and, therefore, need not be detailed. In the largest of these (fig. 1 5 e) the ectoderm of the calyx 

 was thick and yellowish. Four wide, straight nectocalycine canals opened into a circular 

 canal, which surrounded the prominent mouth of the organ. Broad transverse fibres were 

 distinguishable in the thick inner wall. The peduncle of attachment, thick and subcyhndrical, 

 contained a canal which widened at the base of the medusiform body into a cavity whence 

 the four longitudinal canals arose. 



^ Called "cyathiform bodies" in my memoir, communicated to tlie Linnean Society {supra) 

 in 1847. At that time I had not discovered the androphores, which, however, were briefly described 

 and figured in my paper in ' Miiller's Archiv' for 1851, above referred to. 



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