REPORT ON THE DEEP-SEA MEDUSvE. 135 



triangular, pointed velar lobes, or more accurately four pairs ; for the eight adradial and 

 the sixteen subradial incissions of the umbrella margin, as well as the eight principal 

 incisions in which the sense clubs lie, are deeper and stronger than the thirty-two 

 shallower velar incisions inserted between the former and the latter. Moreover, 

 as the adradial middle of the eight velar arches of the umbrella margin projects more 

 strongly than its receding side parts, the sixteen pairs of velar lobes lying on both 

 sides of the eight adradial canals appear larger than the sixteen pairs of weaker velar 

 lobes lying on both sides of the eight principal canals (or of the eight rhopalia). If we 

 add the sixteen smaller ocular lobes to this sixty-four velar lobes, the aggregate number 

 of the marginal lobes amounts to eighty, as in many other Rhizostomse. 



The eight sense clubs show essentially the same conditions of situation, shape, size, 

 and structure which Grenacher and Noll (1876) described minutely in Crambessa tagi 

 (comp. also my System, pp. 458, 615, and Hertwig, Die Sinnesorgane der Medusen, 1878). 

 They are acorn-shaped, and divided by a circular constriction into a club-shaped basal 

 part and an oval distal part, the former contains the csecal distal end of the ocular canal, 

 the latter contains the otolite sac filled with numerous crystals. The sense clubs lie 

 hidden in a subumbral rhopalar niche of the subumbrella, which is roofed over by a 

 broad protective scale and enclosed laterally by the projecting sense folds (" plicae 

 rhopalares," of) ; these are the medial margins of the diverging ocular lobes or sense lobes 

 which project like arches and overlap one another like a valve at their base. Above, on 

 these subumbral surface, the roof-like projecting protective scale or protective plate is 

 hollowed out by a csecal funnel-shaped depression or olfactory funnel (" infundibulum 

 olfactorium," oz), which is traversed by dendritically -branched folds (" olfactory folds"). 

 Tentacles are entirely wanting in Leonura as in all other Rhizostoma. 



The inner side of the umbrella (subumbrella, figs. 2, 4-7) and the umbrella cavity 

 enclosed by it, show the same peculiar and remarkable conditions of structure in Leonura, 

 which recur in all Rhizostoma? Monodemnia? (Versuridce and Crambessida), and which 

 were first described by Huxley (1849) in Crambessa mosaica, and later (1876) in detail 

 by Grenacher and Noll in Crambessa tagi (comp. my System, pp. 472, 615, taf. xxxviii.- 

 xl.). The subumbral umbrella cavity is divided into a peripheric umbrella coronal cavity 

 and a central subgenital vestibule, which communicate only by the four broad 

 interradial subgenital apertures (figs. 1, 7, ig). The latter are separated by the four 

 strong oral pillars (figs. 2, 7, ap), the only connection between the umbrella disk and the 

 arm disk. The coronal cavity of the umbrella forms a tolerably flat, broad coronal furrow 

 of small extent. Its axial inner wall is formed by the external surface of the oral pillars 

 (ap) ; its abaxial outer wall by the subumbral inner surface of the velarium or of the 

 lobed umbrella corona. 



The central subgenital vestibule (" porticus subgenitalis," fig. 2, ir) forms a spacious, 

 though low chamber, whose base form is a quadrate prism. The upper wall or the roof 



