368 bulletin: museum of comparative zoology. 



BouGAiNViLLEiDAE Gegeiibaur. 

 Bougainvillea niobe Mayer. 



Bougainvillea niobe Mayer, 1894, p. 236, pi. 1, fig. 2; 1900, p. 42; 1904, p. 11, 

 pi. 2, fig. 14-14c; 1910, p. 166, pi. 18, fig. 1-3. 



This species was taken at Stations 10,161, 10,162, 10,163, 10,166, 

 10,169, 10,171, 10,172, 10,173, 10,176, 10,178, 10,180, 10,186, 10,188, 

 10,192, 10,195, 10,196, 10,197, 10,200, 10,203, 10,206, 10,208, 10,209, 

 10,211, in hauls with open nets at various depths from the surface 

 down to 1,000-0 meters; a total of about 80 specimens. 



Perhaps no Medusae stand more in need of critical revision than do 

 the members of this genus, for not only are many of the species closely 

 related to one another, but actual observation has proven that some, 

 at least, are merely environmental races of others (Mayer, 1910, p. 

 159); and in all probability some of the more simply organized "spe- 

 cies " are merely the young of the larger and anatomically more com- 

 plex ones. As Mayer points out (1910, p. 159), the "confusion which 

 prevails at present can not be dissipated until the hydroids of all or 

 most of the species are discovered." 



The species recognized by Mayer (1910), and by Hartlaub (1911) 

 in his very useful account of the Bougainvilleas of northern waters, 

 may be divided, for convenience into two groups, those with many 

 (8 or 9) marginal tentacles per bundle, and in which the oral tentacles 

 branch dichotomously five or more times, and those in which either 

 marginal tentacles, or dichotomous branchings of the oral tentacles, 

 or both, are few. The first group includes B. macloviana, B. principis, 

 B. fulva, B. hrittanica, B. superciliaris, B. nordgardii, B. bougainvillei, 

 and B. niobe. Without attempting to settle the relationships of these 

 species to one another, I may point out that B. niohe is easily separated 

 from B. macloviana by the absence of peduncle, and structure of gonads, 

 which are strictly limited to the manubrium; from B. superciliaris and 

 B. bougainvillei (which are probably identical) by the absence of a 

 peduncle; from B. principis by fewer marginal tentacles, and espe- 

 cially by the smaller, narrower, marginal tentacular pads; from B. 

 nordgardii by larger size and presence of ocelli. Bougainvillea niobe, 

 B. brittanica, and B. fulva are closely allied, anatomically, to one 

 another: in all three the bell is high, thick walled, without peduncle, 

 attaining a height of 10-12 mm.; the manubrium short, with broad 

 cruciform basis; there are upwards of 8 marginal tentacles per bundle; 



