HYDROIDA II 



77 



cally in the Norwegian Sea, and lie also comparatively near the submarine ridges. It was therefore 

 most likely that the species should be reckoned, bio-geographically, as belonging to the class of such 

 visitors, and the two new finds appear to confirm this supposition, both being situate in the warmer 

 atlantic region; one on the slope down towards the Atlantic Deep, west of the Faroe plateau, and the 

 other on the east side of the threshold in Danmark Strait, where several other warm-water species 

 also come in. The last-named locality, with a depth of 138 fathoms, is the shallowest of the finds 

 made; the others lie deeper down in the true abyssal region. We are therefore justified in concluding 

 that the species belongs to the warmer and deeper atlantic communities. 



Aglaophenopsis (Fewkes). 



Upright colonies with branched or uubranched main stem, the apophyses bearing unbranched 

 hydrocladia with several hydrothecae. All the sarcothecae are immobile. The gonothecae are protected 

 by minor branches forming a basal appendix to the hydrocladia, and with both hydrothecae and sar- 

 cothecae; the gonothecae are situate on the stem or on the minor branches. 



Practically speaking, this definition coincides with Nutting's limitation of the genus (1900 

 p. 118). Nutting also lays most stress upon the occurrence of the protective branchlets, but does 

 not seem quite to have realised that the principal character for these lies in the fact that they bear 

 hydrothecae, not, as in the case of Cladocarpus, sarcothecae only. Aglaophenopsis differs from Nemalo- 

 cnrpus in principle by the fact that the miner branches do not develope into secondary hydrocladia of 

 normal appearance, but merely appear as protective appendices in fertile colonies. 



Aglaophenopsis-Cladocarpus form a pair of genera parallel with Thecocarpus-Aglaophenia. As 

 a matter of fact, we cannot determine which of the two in each case is the more primitive; having 

 regard, however, to the development of a species such as Nematocarpus ramuliferus, which appears to 

 be more primitive than the others in the state of its gonangia, we must probably incline to the theory 

 that Cladocarpus and Aglaophenia are the more primitive, rather than the more highly developed. 

 Still, we can hardly in either case regard the one genus as derived from the other; it would seem 

 more likely that each has arisen independently. 



Aglaophenopsis cornuta (Verrill) Nutting. 



1879 Cladocarpus cormitus, Verrill, Notice on recent additions to the marine fauna, p. 310. 

 1900 Aglaophenopsis cornuta, Nutting, Plumularidae, p. 120, pi. 30, figs. 6-9. 



Colonies doubly pinnate, with branched polysiphonic main stem, monosiphonic in its extreme 

 portions. The primary stem tube is divided into short internodia, bearing in the middle an apophyse 

 directed obliquely forward and sideways, and three sarcothecae, one pair nearest the upper side of the 

 apophyse, and an unpaired one medially on the lower part of the internodium; all are split along the 

 upper side, and project far forward, especially the paired ones. At the base of the apophyse, between 

 it and the unpaired sarcotheca, there appears a pattern which must be interpreted as an abortive 

 hydrotheca. The hydrocladia have on the rear side a markedly prominent keel; they are divided into 

 short internodia, each bearing a large hydrotheca and three sarcothecae, a supracalycine pair at the 



