HYDROMEDTJSAE, SIPHONOPHORES, AND CTESTOPHORES. 343 



I have already (19115) pointed out that the Diphyopsis weberi of 

 Lens and Van Kiemsdijk was identical with the form long ago 

 recorded by Huxley as Diphyes chamissonis and recently redescribed 

 by Browne (1904) ; and the present series supports this view. 



Huxley's figure (1859, pi. 1, fig. 3) shows that the superior necto- 

 phore of his specimens had all the important external characters 

 which distinguish weberi; that is, prominent dorso-basal and lateral- 

 basal teeth; hydroecium deep, reaching to one-third or one-half the 

 length of the nectosac, and extending well below the bell-mouth; 

 short fusiform somatocyst; and nectosac not constricted apically. 

 The only noticeable difference is that in Huxley's figure the apex of 

 the nectophore is rather blunter than it is shown by Lens and Van 

 Riemsdijk. But we must remember that Huxley drew his figure from 

 living or at least fresh material, whereas the Siboga specimens were 

 studied after preservation. Furthermore the present series shows 

 that there is a considerable range of variation in the acuteness of the 

 apex as well as in the proportion between the breadth of the necto- 

 phore and its length. Therefore this slight difference is merely in- 

 dividual, perhaps the result of contraction. The number of ridges 

 at the apex (five) is constant, as are the other distinguishing char- 

 acters noted above. 



The present specimens agree very well with the accounts by Browne 

 (1904, p. 742, pi. 54, fig. 6) and by Lens and Van Riemsdijk (1908). 

 The stems are invariably broken off, only 2 to 4 of the most proximal 

 and youngest groups of appendages being intact. They are not suf- 

 ficiently advanced to show the buds for special nectophores discovered 

 by Lens and Van Riemsdijk. 



The largest specimen is 12 mm. long, rather larger than the Siboga 

 examples, which averaged 7 mm. long, but about the same size as 

 Huxley's and Browne's. The inferior nectophore of this species is 

 unknown, but Lens and Van Riemsdijk saw the bud for this struc- 

 ture. The detached inferior nectophores which they thought might 

 belong to this species (1908, p. 55) have since proved to be D. mitra 

 (Bigelow, 1911&). 



D. chamissonis is so far known only from the Indo-Pacific — i. e., 

 east coast of Australia and Louisiade Archipelago (Huxley), Malay 

 Archipelago (Siboga), Ceylon, and the Maldives (Browne, 1904, 

 1905), Japan, Sumatra, New Guinea, the Seychelles (Moser 1913), 

 and the Philippines. There are no Atlantic records. 



