EEPORT ON THE DEEP-SEA MEDUSiE. 39 



The auditory clubs in Pegantha pantheon are very numerous, 400 to 450, 20 to 25 upon 

 each of the collar lobes (figs. 1, 2). They are regularly distributed along the bow-shaped 

 umbrella margin, and run inwards immediately into the auditory clasps. The otoporpae 

 or auditory clasps (figs. 2, 4, oo) are all equal in length, nearly three times as long as 

 the auditory clubs ; their axis converges more or less towards the middle point of the lobe 

 base (fig. 2). Their inner end is thickened and rounded like a club ; their exodermal epi- 

 thelium contains many larger and smaller thread-cells. The auditory clubs themselves are 

 larger than in most other Narcomedusse, and contain an axis of three to five, usually four, 

 large endodermal cells, each enclosing a crystal. The proximal otolite (at the thin end of 

 the auditory club) is the smallest, the distal otolite (in the club-shaped rounded end) the 

 largest, and between these one or two medium-sized crystals (in the middle endodermal 

 cells). The auditory club is surrounded by a stiff bunch of auditory hairs (oh), which 

 run out from the auditory pad (op). After treatment with acetic acid and carmine, a 

 nucleus coloured red (perhaps the original cell nucleus enclosed by the formation of the 

 otolite) was visible in the centre of the otolite (fig. 12, ol). The manner in which the 

 auditory clubs and their auditory clasps are disposed upon the umbrella margin, and their 

 relations to the adjacent organs will be best understood by a comparative study of 

 figs. 2 and 4 in Plate XL and figs. 7 and 12 in Plate XII. In fig. 12 especially it 

 is clear how the auditory club rises on a thin stalk from the conical auditory pad (op) 

 of the urticating ring (»c), and how the fulcral lamella (z) between the two nerve 

 rings (?ic) passes through to the base of the auditory club, and thence into its sup- 

 porting plate. 



The gastrovascular system (PI. XL figs. 1,3; PI. XII. figs. 7, 9, 12) is, on the whole, 

 the same as that already described in Polycolpa forskalii (comp. above, p. 34, and 

 PI. XL figs. 1, 3, 6, 8). The stomach also forms a wide, flat, circular pouch, occupying 

 the whole lower side of the umbrella lens (fig. 7, gc). Whilst the slightly convex 

 lower surface of the latter forms the cover of the gastral cavity, its bottom is formed 

 by the very muscular and extensible central part of the subumbrella, which is laid in a 

 large number of radial folds (fig. 9). A short, wide oesophagus hangs down in the 

 middle of the folds, its ample oral opening showing a swollen, thickened oral margin 

 (fig. 7, qg). The peripheric part of the gastrovascular system is formed by the festoon 

 canal, which is composed, in this species, of eighteen separate lobe canals (comp. above, 

 p. 35). The latter run on the inner side of the urticating ring along the margin of the 

 oval collar lobes, and open at their bases immediately into the periphery of the gastral 

 cavity (fig. 3, go). The two openings take in between them the stalk of the genital 

 sacs, which hangs in the relative lobe cavity (fig. 3, oc). The ribbon-shaped flattened 

 canals are nearly one-eighth as broad as the greatest breadth of the lobes. Their sub- 

 umbral endodermal epithelium (fig. 12, div) is composed, as usual, of very high narrow 

 cylindrical cells, whilst that of their umbral wall (cho) consists of many flat, flagellate 



