Fig. 11. — Subumbral view of the entire Medusa (from below), three times the natural 

 size ; one of the two perradial diameters stands vertically, the other horizontally. We 

 look through the wide quadrate oral opening into the gastral cavity, in which the eight 

 conical white, adradial oral funnels project. The sixteen hemispheroidal buccal 

 pouches are visible round the swollen oral margin ; outside these, the eight wide genital 

 sacs. In the peripheric part of the umbrella, the broad velum with its deep circular 

 furrow is shown to the right, the circular muscular layer of the subumbrella and the 

 caecal centripetal canals (11-13 between each two radial canals) to the left (after removal 

 of the velum). The umbrella margin shows the thirty-two groups of sucking-cups, to 

 the left without the longer tentacles, to the right with the latter. 



Fig. 12. — Radial section through the velum (v) and the marginal part of the umbrella 

 with the circular canal (cc) ; slightly enlarged, yc Marginal fold in the circular canal. 

 d& Umbral, dc 2 subumbral endodermal epithelium of the circular canal, mic Muscular 

 folds of the subumbrella (w). qw Ectodermal epithelium of the subumbrella. uf Elastic 

 fibres in the gelatinous umbrella (ug). e Exumbrella. ts Tentacles with sucking-cups. 

 td Tentacles without sucking-cups, no Urticating ring, re Nerve ring, ve, vw, mw, 

 comp. fig. 13. 



Fig. 13. — Radial section through the basal part of the velum, greatly enlarged, vw 

 Subumbral or ventral epithelium, x Layer of vesicular connective tissue, mv Rami- 

 fications of the muscular plate, zv Supporting lamella, ve Exumbral or dorsal epithelium 

 (comp. fig. 12). 



Fig. 14. — Radial section through the deep circular fold of the velum, in the middle. 

 Letters as in figs. 12 and 13. Greatly enlarged. 



Fig. 1 5. — Longitudinal section through a tentacle with sucking cup, slightly enlarged. 

 qt Ectodermal epithelium, nit Muscular plate. zt Supporting plate or fulcral lamella. 

 dt Endodermal axis, ng Gelatinous substance of the umbrella margin, uf Elastic fibres 

 of the gelatinous substance. 



Fig. 16. — A sense club of the umbrella margin greatly enlarged, oh Auditory hairs. 

 ol Otolite (enclosed in the last endodermal cell of the axis). d Endoderm. q Ectoderm. 

 ob Sense pad. 



Fig. 17. — A tactile tentacle, without sucking-cup, slightly enlarged. Letters as in 

 fig. 15. 



Fig. 18. — A tentacle group of the umbrella margin, slightly enlarged, td Tentacles 

 without sucking-cups : ts with sucking-cups, v Velum. 



Fig. 19. — A band-shaped elastic fibre from the gelatinous substance of the umbrella, 

 greatly enlarged. 



Fig. 20. — A piece of the umbrella margin seen from the outside, twelve times the 

 natural size, es Exumbral radial furrow, wm Subumbral circular muscles, cr Radial 

 canal, ce Centripetal canals, cc Circular canals, ts Sucking-cups, td Tentacles with- 

 out sucking- cups. 



