BIGELOW: MEDUSAE AND SIPHONOPHORAE. 431 



(Vanhoffen, 1912, p. 359), occurred, very generally, over the area 

 studied by the Bache (p. 368), with the sole exception of the cold 

 coast water off Chesapeake Bay, but nowhere in large numbers. And 

 as pointed out (p. 369), the series contains both budding and sexual 

 phases. The area in question is probably chiefly peopled with Bou- 

 gainvillea from the Bahamas, but perhaps from Bermuda also. 



The occurrence of Bougainvillea niohe in the south Atlantic (25° S.) of 

 course suggests that it ranges as widely in that ocean as does Cytaeis. 

 But opposed to this possibility is the fact that it was not found at any 

 of the numerous stations of the Plankton or Valdivia expeditions in 

 the north and south Atlantic (Maas, 1893, Vanhoffen, 1913b) ; and 

 that it is not known from the inner edge of the Gulf Stream off New 

 England on the one hand, or from the Canary Islands, or the Medi- 

 terranean, on the other. Its absence in the central part of the Atlantic 

 may be a seasonal phenomenon, for while most of its records are for 

 winter or early spring (January to March), plankton hauls on the 

 high seas have been usually taken in summer. And this is made the 

 more likely by its presence in the inner edge of the Gulf Stream off 

 Chesapeake Bay in January (Station, 10,161), contrasted with its 

 absence there and at corresponding localities further north, in summer 

 (1915, 1917b). But its absence in European waters, especially in the 

 Mediterranean, can not be explained on seasonal grounds, nor can 

 the failure of recent deep-sea expeditions to find it in the Pacific or 

 Indian Oceans. I believe the true explanation to be that this funda- 

 mentally American species is enabled by its budding phase to spread 

 over the western side of the tropical Atlantic; but that the interval 

 between successive hydroid-stages is not long enough for it to attain 

 a wider dispersal. 



The Bache list includes the following warm water holoplanktonic 

 Medusae: — Aglaura hemistoma, Liriope tetraphylla, Geryonia proho- 

 scidalis, Rhopalonema vclatum, Cunina peregrina, Pegantha clara, 

 Pegantha dactyletra, and Solmundella bitentaculaia. And all of the 

 siphonophores, except two new species, of whose faunal relationships 

 nothing is known, and the few cosmopolitan forms (p. 434), likewise 

 belong to this category. Most of these Medusae were already known 

 to have very wide range, Rhopalonema, Aglaura, Lii'iope, Geryonia, 

 and Solmundella being practically universal throughout the warmer 

 parts of all three great oceans; while Pegmitha clara, and probably 

 P. dactyletra, have been recorded from both the Atlantic and the 

 Pacific. Cujiina peregrina was previously known from the Pacific 

 only. But as it covers a very wide range there (Bigelow, 1909a, 1913; 



