DIPHYES SPIRALIS. 249 



The left lateral ridge arises some distance below the apex, usuallj' at about the 

 level of the upper end of the nectosac. In a series of one hundred Pacific and 

 one hundred Atlantic specimens there is no variation except for very slight 

 individual differences in the precise level at which the left lateral ridge arises. 

 Such constancy is in marked contrast to the variability in the number of ridges 

 at the apex in D. bojani (p. 252). 



As long ago pointed out by Gegenbaur ('60), the dorsal ridge, which extends 

 upward from the basal margin, is very short (Plate 9, fig. 6). The serration 

 of the lateral and ventral ridges, so often noticed, is chiefly restricted to the 

 central two thirds of their length. They are smooth near the apex, and as a 

 rule, though not always, close to the basal margin. Besides the ridges, the 

 great length of the somatocyst, the absence of dorsal or lateral teeth, and the 

 basal outline of the hydroecium (Plate 7, figs. 5, 6) are all characters of specific 

 importance. 



The posterior nectophore has so often been figured that I may merely note 

 for read}^ identification, that its hydroecial canal is closed, and that the basal 

 teeth which are prominent, bear smaller teeth in their dorsal margins (Plate 10, 

 fig. 6). 



The Eudoxid of D. nppendiculata is so well known, as to require no descrip- 

 tion here. Agassiz and Mayer have described the Eudoxid of the Pacific D. 

 appendiculata as an "Ersaea," not an "Eudoxia" as it is in the Atlantic form. 

 But Lens and Van Riemsdijk found typical Eudoxia campanula in the " Siboga " 

 material; and the figures of Agassiz and Mayer suggest that what they took 

 for the monogastric generation of D. appendiculata was in reality the "Ersaea" 

 of Diphyopsis dispar (cf. Agassiz and Mayer, :02, pi. 9, fig. 40, witli their own 

 ])!. 10, fig. 41, and with Lens and Van Riemsdijk, pi. 7, fig. 62). 



Diphyes spiralis, sp. nov. 

 Plate 7, fig. 4, Plate 8, fig. 1, 2, Plate 9, fig. 3, Plate 11, fig. 4. . 



Sta' 



ion 4583 surface 7 anterior nectophores. 



Types. 



