250 DIPHYES SPIRALIS. 



The largest is six, the smallest is two mm. long. 



These small nectophores differ so markedly in general from all previously 

 known Diphyids that a new species is necessary to receive them. Their most 

 remarkable feature is that the entire nectophore is spirally twisted, the tortion 

 in all cases being in the same direction as the hands of a clock (Plate 7, fig. 4, 

 Plate 8, fig. 1). This is so pronounced that the specimens, though very small, 

 are recognizable at a glance. In contracted individuals (Plate 7, fig. 4) the tortion 

 is so extreme as to render resolution of the facets and ridges extremely difficult, 

 but on expanded material (Plate 8, fig. 1) these can be easily followed. There 

 are four ridges at the apex (Plate 8, fig. 2), dorsal, ventral, and a lateral on either 

 side. Owing to the general tortion the dorsal lies to the left, the ventral to the 

 right of the mid-line. The dorsal and lateral ridges run to the basal margin 

 without branching, following a spiral course, more easily represented in the 

 drawing than by description. At the margin the dorsal ridge is nearly dorsal, 

 but the left lateral lies dorsal, the right lateral ventral, to the mid-ventral line. 

 The ventral ridge bends at first sharply to the right, and then divides into two, 

 which enclose a ventral facet. The right hand one of the two resultant ridges 

 runs obliquely to the left, so that it reaches the basal margin of the hydroecium 

 near the mid-ventral plane. The left ventral ridge follows a corresponding 

 parallel course, but at about the level of the opening of the nectosac it bends 

 sharply toward the mid- ventral plane, and terminates (Plate 8, fig. 2), so that 

 the ventral and left ventrolateral facets become confluent. All the ridges are 

 strongly serrate, except near the apex. The arrangement of the ridges is con- 

 stant in all the specimens examined, except for greater or less twisting, con- 

 comitant with greater or less contraction. But even in specimens which had 

 lost the musculature of the subumbrella, and were consequently fully expanded, 

 the tortion is well marked. There are neither basolateral nor basodorsal teeth 

 in this species. 



The hydroecium is rather short, and pointed at the apex; its base shows 

 an asyrmnetry so characteristic that it is possible to identify the species from 

 this region alone. Its basolateral margins are strongly concave (Plate 8, fig. 1) ; 

 each ends dorsally in a pronounced tooth. The dorsal wall below the le\'el 

 of the bell opening is divided so as to form two lanceolate wings of which the 

 right hand one is much the larger in all our specimens. The ventrobasal wall 

 of the hydroecium is deeply incised in the mid-line, where the right ventral ridge 

 reaches it, and the entire basal margin of the hydroecium is strongly serrated. 



The somatocyst, which is cylindrical and rather more than half as long as 



