84 THE VOYAGE OF H.M.S. CHALLENGER. 



secondary folds lie in each transverse fold. The interspaces between these folds perhaps 

 develop into special genital sinuses with excretory passages opening into the pouch 

 space and from there into the ring sinus, which probably comport themselves as in the 

 complicated forms of the Lucernaridaa. The complicated structure of this many-folded 

 genital band, is, however, as in the Lucernaridae, very difficult to make out. In the 

 single specimen of Periphylla mirabilis before me, the ripe pouches of the testes were 

 already flattened for the most part, and the spermatozoa emptied into the coronal sinus. 

 The small follicles of the testes which, closely placed together, compose the folded genital 

 band, are placed in 3-4 layers, the one above the other, and have an irregular roundish 

 polyhedric shape, and measure 6, I/O, 5' in diameter. Each single follicle (fig. 40) is 

 surrounded and separated from the others by a thin fulcra! lamella containing nuclei (zs). 

 In transverse section, under stronger magnifying power, we see that the larger mother- 

 cells of the spermatozoa (sd), which arise from the endodermal epithelium of the sinus 

 wall, line the wall of the follicle, whilst the centre is filled by the ripe spermatozoa (PI. 

 XXIII. fig. 40 sz). 



Periphema} Hseckel, 1877. 



Peripkyllidae, with four perradial buccal pouches of the oesophagus and four perradial 

 niches of the basal stomach, united in its aboral basis. Between the niches, the four 

 subumbral funnel cavities (or the four hollow interradial tseniola of the basal stomach) 

 form hollow cones, which are beset with two rows of gastral filaments, but are free from 

 them above each end, separated below the point of the cone. 



I established the genus Periphema in 1877 (in the Prodrornus Systematic 

 Medusarum) for a large Periphyllid, of which there were, unfortunately, only broken and 

 incomplete fragments of a single, very large specimen in the Challenger collection. I 

 was, however, able by careful examination of these fragments, and with the help of other 

 Periphyllidse examined by me (viz., by comparison with the large, perfectly preserved 

 specimen of Periphylla mirabilis), to compose a complete quadrant of the Medusa from 

 the fragments, from which the figure in Plate XXIV. is drawn in its natural size. The 

 reconstruction was more difficult, as the enormously developed proboscis or buccal stomach 

 (fig. 3) was completely torn away from the pylorus and broken in pieces, and there 

 were also distracting abnormal deformities — clearly in consequence of an earlier but 

 completely healed injury — on the only remaining quadrant of the subumbrella (fig. 1), 

 which I have of course left out in the figure. Apart from these, our Periphylla regina 

 seems very closely allied to the preceding Periphylla mirabilis, and I therefore included 

 it without hesitation in this genus in my System (1879, p. 421). However, I now 

 consider it more appropriate to separate it generically from Peripiliylla regina under the 



1 Yltqttpnfios = greatly renowned. 



