230 BASSIA BASSENSIS. 



46G3, 4665, 4667, 4669, 4671, 4673, 4714, 4715, 4716, 4743, and in Acapulco 

 Harbor; both surface and 300 fathom hauls; about 180 specimens. 



In the largest specimen the superior nectophore is 5 mm. long, the inferior 

 one 8 mm. long. 



The material as a whole is in very good condition. After comparing it 

 with numerous Atlantic specimens, as well as with the descriptions and figures 

 of Gegenbaur and Haeckel, I have been unable to find a single difference suffi- 

 ciently constant to warrant the recognition of but one species. The same con- 

 clusion was reached by Bedot ('96) for specimens from Amboina, and I can bear 

 out his observations as to the variability of the outlines of the two nectophores 

 and their proportions, and of the inclination of the anterior one. Lens and 

 Van Riemsdijk have summarized the historj^ of the species; but as their 

 material was too fragmentary for satisfactory identification they retain a 

 Pacific and an Atlantic species. 



B. basscnsis has been well described and figured by Huxley, Gegenbaur, 

 and Haeckel. Its most diagnostic features are the form of the posterior necto- 

 phore which is quadrilateral, the right lateral ridge entirely suppressed except 

 at its basal extremity, and especially the coalescence of the two ventral wings, 

 by which the hydroecium is closed for the upper two thirds of its length. 

 This feature alone is sufficient to distinguish B. bossensis from all species of 

 Abyla and Abylopsis. 



The anterior nectophore resembles that of A . pentagona and A . eschscholtzii, 

 in the general arrangement of its facets and ridges. But it is easily distinguished 

 from them, because in it the base of the hydroecium does not project as it does 

 in those species. This difference is more readily illustrated by figures than by 

 description (Plate 14, fig. 1, 6, 9). Huxley long ago suggested that his Sphen- 

 oides australis was the free Eudoxid of B. bassensis, and both Chun ('88) and 

 Haeckel ('88b) have observed the actual development of the cormidia of this 

 species into "Sphenoides." In many of the "Albatross" specimens the bracts 

 are sufficiently developed to show that they are undoubtedly the younger stages 

 of S. australis; and the same was true of Haeckel's material ('88b, pi. 38). There- 

 fore there is no longer any excuse for retaining the name Sphenoides australis. 

 The young bracts, as shown in Haeckel's figures ('88b, pi. 38, fig. 13, 14), have 

 more prominent angles and ridges than the older ones, and the same is true of 

 the gonophores. The bract in the largest "Sphenoides" is 9 mm. long. The 

 Eudoxid described by Bedot as Parasphenoides amboinensis, in the extreme 

 development of its ridges and angles, suggests the bracts of B. bassensis while 



