HIPPOPODIUS. 207 



At the apex in the younger nectophore there are eight radial canals (Plate 3, 

 fig. 4) ; but these all branch dichotomously at different distances from their 

 points of origin ; and the resultant canals anatomose by means of short transverse 

 trunks until they form an irregular reticulum covering the subumbrella surface 

 (Plate 3, fig. 2). Fortunately in this one example the nectosac was in such good 

 condition that the canals could be traced over most of its surface with ease. 

 To make certain that the ridges actually represent canals, serial transverse sec- 

 tions were cut of two adjacent ones, and in each the open lumen, surrounded 

 by entoderm, was visible. 



Bract. Of course, in the entire absence of the stem, the identity, with P. 

 reticulata, of the bracts (Plate 3, fig. 6) is rather doubtful. They are referred 

 to it because of their occurrence in the same haul, and because they differ from 

 the corresponding structures yet described for any other Praj'id, in their large 

 size (20 mm. in length), and lateral flattening. 



The condition of the somatocyst and of the subumbral canals in the j'oung 

 nectophore (Plate 1, figs. 7, 8) suggest that it is a young stage of P. reticulata. 

 The somatocyst is thicker, its lateral branches proportionately stouter, and its 

 ventrodorsal arm bends posteriorly corresponding to a curving of the nectophore 

 as a whole. The subumbral canals are evidently radial, and the development 

 of cross-trunks has not proceeded so far as in the older nectophores. But the 

 condition in the latter may be easily derived from the former by progressively 

 increasing anastomosis. Indeed the beginnings of the process are clearly fore- 

 shadowed by the few transverse canals which already connect several of the 

 radial canals. The general form, and the well-developed hydroecium extending 

 from end to end, also suggest that the specimen is a young nectophore of N. 

 reticulata. 



Hippopodiidae Kolliker, 1853. 



Following (Chun, '97bj two genera, Hippopodius and Vogtia, are recognized. 

 Schneider ('98) has united these. But though they are no doubt closely allied, 

 the difference in the structure of the nectophores seems of more than specific 

 importance. Were subgenera recognized, Vogtia would be considered one. 



HIPPOPODIUS QuoY and Gaimard, 1827. 



For the reasons for the use of this name rather than Gleba, see Chun ('97b) 

 and Schneider ('98). Chun recognizes two species of Hippopodius, the well- 

 known Atlantic and Mediterranean form so often described under the names 



