Fig. 1. — The entire Medusa (profile view), natural size. The upper half of the 

 umbrella is occupied by the smooth, thick-walled umbrella cone (" conus umbralis "), 

 whose thick gelatinous wall is traversed at the point by the basal peduncle canal. A 

 perradial (lanceolate) niche of the basal stomach, enclosed by two conical basal (inter- 

 radial) funnel cavities, shines in the middle through the upper half of the umbrella 

 cone. A perradial (narrowly lanceolate) gastral opening, having a pair of yellowish 

 testes on either side, shines in the middle through the lower half of the umbrella cone. 

 A deep circular stricture is formed at the middle of the height of the umbrella, by the 

 coronal furrow, at the bottom of which circular fibres of the exumbral zonal muscles are 

 indicated. The umbrella corona ("corona umbralis "), which occupies the entire lower 

 half of the umbrellas begins below the coronal furrow. The upper half of the umbrella 

 corona (or the pedal zone) is formed by the sixteen thick gelatinous sockets or pedalia, 

 which are separated by sixteen subradial longitudinal furrows, whilst the lower half of the 

 umbrella corona (or the lobe zone) is formed by the corona of lobes, tentacles and sense 

 clubs, which are fastened at the distal margin of the gelatinous pedalia. The four 

 interradial sense clubs he on four narrower and shorter ocular pedalia, whilst the twelve 

 tentacles (four perradial and eight adradial) are borne by broader and longer tentacular 

 pedalia. The sixteen subradial coronal lobes consist of a thick oval gelatinous plate 

 divided by a deep (precisely subradial) longitudinal furrow of the exumbrella into two 

 limbs, and of a broad, thin membraned marginal selvage (patagium). The four pairs of 

 ocular coronal lobes are longer but narrower than the four pair of tentacular lobes. The 

 twelve tentacles form four groups, each consisting of a middle (perradial) and two lateral 

 (adradial) tentacles. A strong longitudinal muscle is visible on the (axial) side of each 

 tentacle, whilst the outer abaxial side shows transverse constrictions (comp. fig. 7, 

 PI. XIX.). 



Figs. 2-5. — A sense club (rhopalium) seen from four different sides, moderately 

 enlarged, in the natural position, with the point of the protective scale directed downwards, 

 listalwards. Fig. 2. Axial view (from inside). Fig. 3. Abaxial view (from outside). 

 Fig. 4. Profile view (from the side). Fig. 5. Oblique view (half from inside, half from 

 the side). The letters have the same meaning in all four figures, oa Ampulla rhopalaris, 

 below it the two limbs of the peduncle of the rhopalium. op Collar-shaped pigment pad 

 with two limbs, closed like a circle below, oc' Axial unpaired eye with lens, between the 

 limbs, oc" Abaxial paired eye. og Protective scale of the rhopalium. on sense niche 

 on the hollow axial surface of the scale, ok Stalked auditory club. 61 Spheroidal otolite 

 sac with crystals. 



c 



