REPORT ON THE DEEP-SEA MEDUSAE. 67 



thin, folded, wing-shaped membranous selvage (" patagium," lj)), 5-8 mm. broad, also 

 runs round the margin of this lobe ; it is broadest at the point and narrowest at the base 

 (fig. 1, 22, &c). 



The fused clasp of the marginal lobes (" loboporpa, cathamma lobare," hi; PI. 

 XXII. fig. 22 ; PL XXIII. fig. 29). The exumbral longitudinal furrow of each lobe, 

 which divides its two gelatinous swellings and passes above into the" sulcus interpedalis," 

 has a corresponding fused clasp (hi) in the interior of the lobe. This is a rectilinear 

 gelatinous selvage of cartilaginous hardness, firmness, and elasticity. It springs with a 

 broad basis (fig. 29, hi) from the proximal margin of the coronal muscle, and reaches the 

 border of the middle and distal third of the lobe, where it becomes thicker and ends (fig. 

 22, hi"). Its peculiar structure is shown in Plate XXV. fig. 10, under a higher magnifying 

 power. The clasp is formed by the umbral or abaxial endodermal epithelium (fig. 10, dw) 

 and the subumbral or axial endodermal epithelium (fig. 10, dw 2 ) becoming fused into 

 sixteen subradial straight lines in the peripheric part of the circular sinus, by which the 

 latter is divided in the region of the coronal muscle into sixteen coronal pouches (be). 

 The fused clasp of the marginal lobes completely divides the two adjacent coronal 

 pouches, but only partially divides the lobe pouches proceeding from them (PI. XXV. 

 fig. 10, bl), which are bent into each other like a horse-shoe at the thickened distal end of 

 the clasp (bu, figs. 22, 29). Both the thicker gelatinous plate of the umbrella 

 (PL XXV. fig. 10, ng) and the thinner gelatinous plate of the subumbrella (zw) undergo 

 considerable induration and peculiar histological change in the region of the fusion of the 

 two layers of endodermal epithelium. The soft gelatinous substance becomes a firm 

 fibrous cartilage with numerous roundish cells separated by a fibrillar intersubstance. 

 The fibrous cords of the intercellular substance cross each other in all directions, as they 

 do in the analogous cathamma of the nodes of the septa (PL XXV. fig. 4, hi). 



The sixteen tentacles (PL XXVIII. fig. 1 ; PL XIX. figs. 6, 7 ; PL XXI. fig. 21 ; PL 

 XXII. fig. 22) are strong, hollow cylindrical tubes, which gradually decrease conically 

 towards the distal point. All the twelve tentacles (four perradial, eight adradial) are of 

 equal size. They are from 30-40 cm. long, consequently twice the height of the 

 umbrella ; they are possibly 50-60 cm. long in the living animal. The tentacles are 

 8 mm. thick at their enlarged conical bases ; 3 cm. below the insertion they are 5 mm. 

 thick ; 5 cm. below only 3 mm., and so gradually decrease towards the point which runs 

 out almost to a thread. The smooth upper surface of the cylindrical tube appears 

 repeatedly constricted by numerous annular folds, which are only interrupted by the 

 longitudinal muscles (figs. 1, 6, 7). The spacious cavity of the tentacles is enclosed by a 

 thin but very firm leather-like wall. 



The tentacle wall is formed of four layers (PL XXI. fig. 21):— (1) the endodermal 

 epithelium (d r ) of the canal (ct) ; (2) the supporting plate (z) ; (3) the muscular plate (m) ; 

 (4) the ectodermal epithelium of the outer surface (q). The finer structure of the wall is 



