128 THE VOYAGE OF H.M.S. CHALLENGES. 



thirty-two bunched ribs of the subumbrella is dichotomised nearly three to four times, so 

 that the number of its distal terminal branches (at the subumbral coronal furrow) 

 amounts to from eight to twelve ; all the bifurcate branches are extended straight, and 

 only diverge slightly outwards at very sharp angles, so that the terminal branches lie 

 nearly parallel to each other, only separated by narrow radial furrows. The secondary 

 and tertiary furrows between the bifurcate branches are much narrower and shallower 

 than the deep, broad furrows between the separate bunched ribs (comp. the quadrant, left, 

 below in fig. 1). 



The tentacles are very numerous (nearly 500-600) ; they lie scattered over the whole 

 extent of the subumbral tentacle zone and spring from its radial furrows, between its 

 ribs. The tentacles appear, at first sight, scattered very irregularly over the whole 

 extent of the broad tentacle zone ; closer examination, however, shows that they are distri- 

 buted quite regidarly. In each octant, there is first an adradial tentacle, usually inserted 

 proximal wards in the middle between every two principal ribs, at the proximal end of the 

 adradial subumbral furrow ; this is probably the original tentacle of the Ephyra, usually 

 migrated inwards. Next follow two subradial tentacles, lying rather further outwards, in 

 the distal end of the two subradial suburnbral furrows, which lie exactly in the middle 

 between the eight adradial and the eight principal furrows of the subumbrella. Outside 

 these three strong, innermost tentacles of each octant of the umbrella, which separate its 

 four bunch ribs, at the distal end, come four more tentacles in the angles of bifurcation of 

 the ribs. The number of tentacles increases towards the outside, corresponding to the 

 repeated bifurcation of the bunched ribs; they always spring at the angle of the bifurcation 

 in the depth of the radial furrow, between each two bifurcate branches. On the whole, 

 fifteen to twenty tentacles may come on each bunched rib, but their number cannot be 

 fixed exactly, as they become smaller, and less distinct towards the peripheric coronal 

 furrow, and at last only appear between the ribs, as unimportant vesicular evaginations 

 of the radial pouches. If we draw concentric circular lines, through the insertions of 

 the tentacles on the subumbrella, an innermost proximal circle will be formed by 

 the eight adradial tentacles, a second circle by the sixteen subradial tentacles ; then 

 a third circle of thirty-two tentacles, which are placed in the first bifurcation of the 

 thirty-two bunch ribs, and so on. The distribution becomes irregular towards the outside. 

 The tentacles are quite cylindrical, often swollen like a club at the end, and seem to be 

 of the same nature as in Cyanea. Their length and thickness appears very unequal. 

 In the specimens before me, most of the tentacles are short (clearly torn away), the 

 longest are longer than the diameter of the umbrella ; the thickness in the thickest 

 tentacles amounts to from 1-2 mm., sometimes to 3-4 mm. ; but numerous smaller 

 tentacles, thick as a thread, are placed between them. 



The peripheric lobe zone of the subumbrella (or the velarium, which may be also 

 termed "rhopalar zone") is 25 mm. broad, and therefore occupies nearly one-third of 



