The pedalia are in reality processes belonging to the _subumbrella_, as will be shown in the section treating of the vascular lamella. They are composed chiefly of gelatine covered with thin surface epithelium and carrying within the gelatine the basal portion of the tentacle canals. They have received various names at the hands of the writers. Gegenbaur called them “Randblätter.” Claus gave them the name of “Schirmlappen,” and incorrectly homologized them with the marginal lobes of other Acraspeda. Claus’s error was corrected by Haeckel, who termed them “Pedalia” or “Gallertsockel,” and homologized them with the pedalia of the Peromedusæ. Besides furnishing a base of support for the tentacles they may perhaps also serve as steering apparatus, a function for which their thin blade-like form would be admirably adapted. Internal to the base of each pedalium, between it and the velarium, is found a funnel-shaped depression of the ectodermal surface. This is shown in Fig. 5 (_ft_) in longitudinal section, and in cross-section in Fig. 16. In the latter figure the epithelium of the outer wall of the funnel (_mt_) is shown much thickened, the result of a stout development of muscle fibres. These are the muscles that in the preserved specimens cause the inward contraction of the pedalia referred to above. 4. _Sensory Clubs_ (marginal bodies, rhopalia). In spite of their position above the bell margin, the four sensory clubs, representing as they do transformations of the four perradial tentacles, are properly classed with the pedalia and interradial tentacles as appendages of the margin. They lie protected in somewhat heart-shaped excavations or niches in the perradial areas of the exumbrella. Each sensory niche is partially roofed over by a covering scale, a hood-like projection from the exumbrella. Below the covering scale the water has free access to the niche and to the sensory club within it. The sensory club consists of a hollow stock directly homologous with tentacle and canal, and a terminal, knob-like swelling, the sensory portion proper. The latter contains on its inner surface--the surface turned towards the bell cavity--two complicated unpaired eyes with lens, retina, and pigment, lying one above the other in the median line; and at the sides of these, two pairs of small, simple, pigmented, bilaterally symmetrical eye spots. At the end of the club, that is, on its lowermost point, lies a sac that contains a concretion and is usually considered auditory. The canal of the stalk is directly continuous with the gastro-vascular system. In the swollen knob of the sensory club it forms an ampulla-like terminal expansion.