REPORT ON THE DEEP-SEA MEDUSAE. 95 



gelatinous folds, formed by a visible, perradial thickening of the gelatinous supporting 

 plate, and stretching from the sense depression to the free margin of the velum. They 

 keep the velarium suspended horizontally, and can raise it still higher by contraction of 

 their longitudinal muscles. The velarium is divided by the four perradial frenula on the 

 one hand and the four interradial pedalia on the other, into eight adradial octants or 

 " velar lobes." These are homologous in position and morphological importance, with 

 the eight free marginal lobes of the Pericol'pa, and the eight arms of the LucernaridEe 

 (comp. Lucernaria, Pis. XVIL, XVII., and also my System, taf. xxii., xxiii.). Hence 

 we see that the velarium of the Cubomedusas corresponds to a corona of eight fused 

 adradial marginal lobes. 



The umbrella cavity (figs. 2-6) is almost cubical, corresponding to the subumbrella. 

 Its four vertical sides are formed by the subumbral walls of the four radial pouches, the 

 upper surface by the subumbral gastral walls ; the lower surface is occupied by the 

 umbrella-opening, which is strongly contracted by the projecting velarium. The 

 stomach hangs down iu the axial space of the umbrella cavity ; its peripheric space is 

 divided above into four small interradial funnel cavities (" infundibula"). These are 

 formed in the upper (proximal) part of the umbrella cavity in such a way that they 

 stretch across the four perradial mesogonia (which we shall describe below) from the 

 four corners of the stomach to the middle of the four radial pouches. The frenula of the 

 velarium correspond to these proximal suspensors in the lower distal part ; four corre- 

 sponding niches are sunk as velar funnels between the frenula. The horizontal 

 diameter of the umbrella disk is consecmently smallest in the four centripetal projecting 

 perradial lines, largest in the centrifugal projecting interradial lines (along the cathammal 

 septa) ; the former correspond to the lateral lines of the quadrate, the latter to the 

 diagonal lines. 



The pedalia, or gelatinous sockels (figs. 1-5, tvi), are four peculiarly-shaped inter- 

 radial gelatinous appendages of the umbrella margin. They bear the tentacles at the 

 distal end, and are sharply defined from them. Gegenbaur terms the sockels of the 

 Charybdea " marginal leaves," Fritz Muller " processes of the corner swellings," and Claus 

 " umbrella lobes." Claus compares them erroneously with the marginal lobes of the 

 other Acraspeda. But these true marginal lobes never He in the principal radia of 

 the first and second order (perradial and interradial), but always between them. On 

 the other hand, the peculiar pedalia of the Cubomedusae always he interradially, and can 

 only be compared to the pedalia in the Peromedusas, which bear both tentacles and sense 

 clubs (comp. above, p. 65). In our Cliarybdea murrayana (figs. 1-5, tvi) the pedalia 

 are cuneiform or trilaterally prismatic in the upper third, compressed laterally in the two 

 lower thirds, and shaped like a thin longish oval leaf, nearly a third as long as the height 

 of the umbrella ; its axial edge is curved concavely, its abaxial edge convexly, whilst its 

 lateral surfaces appear bent unsymmetrically. The tentacle springs from its truncated 



