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BISCAYAN PLANKTON. 

 Part XIII.— THE SIPHONOPHORA. 



By Henry B. Bigelow, Museum of Comparative Zoology, Cambridge, Mass. 

 (Communicated by G. Herbert Fowler, Ph.D., F.L.S.) 



(Plate 28.) 



Bead 3rd November, 1910. 



List of Spbcies. 



Page 



^ectopyramis tJietis, gen. sp. nov 338 



Muggicea Jcochii 340 



Rosacea plicata 341 



Diphyes subtilis 343 



Diphyes ap>pendiculata 344 



Diphyes fowleri, sp. nov 346 



ChunipJiyes multidentata 348 



Hippopodiiis Mppopus 350 



Yogtia pentacantha 351 



? Vogtia spinosa 351 



Rhizophysid, species ? .'552 



Bathymetrical Distribution 352 



Bibliography 355 



Except for a single unrecognizable rhizophysid fragment the collection consists 

 exclusively of Calycoplioraj. A similar absence of the Physophorae in the Atlantic 

 during the summer has been noted by Chun (1897 &), who has suggested that either 

 the adults or the larvae must be at considerable depths at this time of the year. The 

 Biscayan collection throws no light on this question, since no larval physophorids were 

 taken, in spite of the considerable number of hauls from comparatively great depths. 

 The scarcity of physojihorids is not a phenomenon common to the whole of the North 

 Atlantic during the summer months, for, along the eastern coast of North America, it 

 is during this season chiefly that they are encountered. 



On geographical grounds the records are valuable, because very few siphonophores 

 have ever been recorded from the Bay of Biscay, and because several were captured 

 in closing-nets. 



The most interesting features of the collection from the systematic standpoint are a 

 new species of Diphyes, and a new genus, Nectopyramis, probably belonging to the 

 Mouophyidae, but easily distinguished by structural features. 



The classification followed in the ensuing pages is that proposed by Chim (1897 b), 

 and since adopted by Lens and Van Riemsdijk (1908). For a very different scheme, 

 see K. C. Schneider (1898). All the species here Listed, with the single exception of 



SECOND SERIES. — ZOOLOGY, VOL. X. 54 



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