290 NECTALIA LOLIGO. 



These considerations lead to the conclusion that Nectalia and Physophora 

 represent diverging lines of development, of which the latter has progressed 

 much the further from the ancestral state. The most satisfactory way to express 

 this concept in terms of classification is to institute a subfamily of Agalmidae 

 for Nectalia, while retaining the separate family Physophoridae for Physophora. 



NECTALIA Haeckel, 1888. 



Nectalia loligo Haeckel. 



Plate 20, fig.s. 4, 5. 



Nectalia loligo Haeckei.,'8Sii, p. il; '88b, p. 352, pi. 13; Chun, '97b, p. 37, taf. 3, figs. 1, 2; Schneider, 

 '98, p. 124. 



Station 4717 in the trawl from 2153 fathoms 1 specimen in fairly good 



condition. 



The measurements of this example are: — Length of contracted nectosome 

 12 mm.; of siphosome about 5 mm.; of the longest bract 54 mm.; breadth of 

 nectophore 13 mm. This, as is shown by the number of nectophores, bracts, 

 and siphons, is a younger individual than the one figured by Haeckel, but I 

 have found no reason to separate it specifically. 



Nectosome. I was especially glad to find that the pneumatophore was 

 intact and so transparent that its internal anatomy could be worked out in 

 optical section, since Schneider ('98) has suggested that Chun might have over- 

 looked a secondary porus. Most careful search confirmed Chun's account in 

 failure to reveal the slightest trace of any such opening. The chitin ring figured 

 by him ('97b, taf. 3, fig. 1), is clearly visible, as is the secondary ectoderm of 

 the pneumatosaccus. 



There are only four fully formed nectophores, instead of nine, as in Haeckel' s 

 figure; their rounded shape, the dilated nectosac and the course of the sub- 

 umbral canals (Plate 20, fig. 5) agree closely with his account. 



Siphosome. Immediately below the most distal nectophore there are 

 two small bracts on the opposite side of the stem, and the bud for a third. These 

 lie above the "blastocrene," or zone of proliferation for the siphons. The 

 upper bracts are much thicker than the larger ones which lie below, though 

 they agree with them in being distally tridentate. They correspond to the more 

 numerous small bracts observed by Haeckel. In the "Albatross" example 

 they are both much crumpled. Immediately below the small bracts is the 

 zone of proliferation for palpons and siphons, bearing several small buds. Below 



