REPORT ON THE DEEP-SEA MEDUSA. 43 



The velum (v) in JEginura, as in the other iEginidse, is tolerably broad and strong, 

 though not so thick and muscular as in the Cunanthidse and Peganthidse. Nor does it 

 form the peculiar lateral points which project vertically into the deep peronial incisions 

 of the umbrella margin, between each two collar lobes, as in the last-named families. 

 As the collar lobes in the iEginidse are not divided, but united below as far as the 

 umbrella margin by the peronial plates, the velum is nearly of equal thickness through- 

 out, and only slightly broader at the eight principal points where the peronia rise out 

 from the eight corners of the umbrella margin (PL XIII. figs. 2,v; 4, r). 



The umbrella margin (fig. 2) appears regularly octagonal from the slight curvings 

 above mentioned at the principal points where the distal ends of the peronia and peronial 

 plates run out from the urticating ring of the umbrella margin. Its cylindrical urticat- 

 ing ring is limited inside by the velum, outside by the distal margin of the exumbrella, 

 above by the annular canal, and below by the double nerve ring. The sixteen subradial 

 auditory clubs are placed on the abaxial external surface of the urticating ring, between 

 the lower margin of the gelatinous umbrella and the upper margin of the velum, whilst 

 the eight tentacles are inserted much further up on the exumbrella, at the height of the 

 covering of the stomach. 



The sixteen auditory clubs ("cordyli," PI. XIII. figs. 1-3, ok) are placed strictly sub- 

 radially, i.e., they lie in the sixteen radial meridian planes, exactly in the middle between 

 the eight adradial planes of third order, and the eight principal planes, in which the four 

 interradial tentacles (second order) and the four perradial tentacles (first order) are placed. 

 The auditory clubs are placed upon a hemispherical auditory pad (fig. 3, op), a wart-like 

 swelling of the urticating ring, which apparently conceals a "ganglion acusticum;" at least 

 the ganglion cells of the dorsal nerve ring are much more thickly accumulated there (fig. 

 10), and are connected immediately by numerous fine nervous fibrillae, with the high 

 cylindrical sense cells covering the auditory pad. A thick bunch of very long, fine 

 auditory hairs radiate from the pad (fig. 3, oh). The auditory club, which is very thin 

 at the base and considerably enlarged at the distal end, is placed in the axis of the conical 

 bunch. Its endodermal axis consists of 5-6 chordal cells, of which the 2-3 proximal 

 are very small and without otolites, but the 3-4 distal very large, and enclose otolites. 

 The largest otolite in the terminal endoderm cell is sometimes nearly half as long as 

 the whole auditory club. The ectodermal covering of the latter is divided from the 

 endodermal axis by a delicate fulcral lamella (2), and consists of flat sense cells 



(%• 3, q). 



The eight tentacles are inserted high up on the exumbral surface, far from the 

 umbrella margin, and only connected immediately w T ith it by the eight long, strong 

 peronia. A conical tentacle root (fig. 11, br) runs inwards from the point of insertion 

 (at the proximal end of the peronial furrow), horizontally and centripetally, into the 

 gelatinous substance of the umbrella, whilst the peronium (em) goes downward almost at 



