REPORT ON THE SJPHONOPHOR^E. 287 



and- decrease gradually in size from the axial to the abaxial margin of the pedicle. The 

 distal or abaxial end of the horizontal main canal (ns) of the pedicle passes over into the 

 canal-cross which is formed by the four radial canals of each nectophore. The jelly- 

 lamella of the pedicle is covered on both sides by a strong muscular plate composed of 

 horizontal parallel bundles of radial muscle-fibres, which run parallel to the upper and 

 lower margins of the pedicle (fig. 31, nm). The surface of the muscular plate is covered 

 by a flat pavement epithelium of the exoderm. 



The arrangement of the nectophores arouud the trunk is different in the various 

 genera of Auronectse. All the swimming-bells lie in a single horizontal plane, radially 

 arranged, in Stephalia and Auralia (PL VII. figs. 39, 40, 48). But in Stephonalia and 

 in the larger Rhodalia, where they are much more numerous, they compose probably 

 three alternating horizontal rings, as is supposed in the semi-diagrammatic figures 

 (PL III. figs. 13, 14). In the specimens preserved in spirit examined, the majority of the 

 nectophores were detached from the ccenosome and their form much altered by contraction. 

 The remaining axial parts of their pedicles, however, densely placed parallel in regular 

 narrow intervals, allowed their arrangement around the trunk to be recognised with great 

 probability (PL I. fig. 1 ; PL III. figs. 13, 14). Therefore, this may be very similar to 

 that of Forskalia among the Physonectae (PL VIII.), with this difference, however, 

 that in Forskalia the common stem is much longer and more slender than in Rhodalia. 

 Therefore, the spiral column of the nectophores in the nectosome is here much broader 

 and not so high as in the former. The nectophores of the living adult Rhodalia 

 compose probably three transverse series, disposed quincuncially, and so alternating, 

 that those of the first and third transverse series are placed in the same meridional plane 

 of the stem, whilst those of the second transverse series are interpolated between the first 

 and third. But this quincuncial arrangement is only produced by mutual pressure and 

 dislocation of the nectophores, the basal pedicles of which form a single corona (fig. 14). 

 Probably the form of the pear-shaped nectophores is polyhedral by mutual compression 

 in the living animal, whilst it is more roundish in the contracted spirit specimens. 



Each nectophore is a medusiform bell, the pear-shaped umbrella of which is 

 composed of a rather thick and firm jelly-plate. Its inside is covered by a strong 

 muscular subumbrella, composed of circular fibres. The entrance (figs. 6, 16, w) into the 

 wide cavity of the nectosac is closed in the periphery by a broad circular velum, which 

 projects from the margin of the umbrella (figs. 13, 16, v). The entire surface of the 

 nectophores, as well the outside (exumbrella) as the inside (subumbrella), is covered by 

 a flat pavement epithelium. The main axis of the nectophores is radial to the vertical 

 main axis of the trunk, and therefore horizontal in the middle transverse row of 

 nectophores ; it is somewhat ascending in a centrifugal direction in the upper row, and 

 somewhat descending in the lower row (figs. 13, 14). 



The nutritive canal-system of each nectophore (PL IV. fig. 17, n) is, as usual, 



