The meaning of the letters is the same throughout. 



a Oral opening. 

 bg Perradial gastral pouches. 

 bl Lobe pouches (ovaries). 

 ck Peronial canals. 

 cm Marginal canals. 

 d Encloderm. 



du Umbral epithelium of the festoon canal. 

 dw Subumbrella epithelium of the fes- 

 toon canal. 

 cc Coronal furrow of the exumbrella 

 en Peronia or umbrella clasps. 

 er Perradial ribs of the exumbrella. 



Peronial furrow of the exumbrella. 



Central stomach. 



(Esophagus. 



Umbral wall of the central stomach. 



Subumbral wall of the central 

 stomach. 



Umbrella cavity. 



es 

 gc 



yt 



gu 

 gw 



h 

 hi 



Cavities of the marginal lobes. 



mp Peronial muscle (perradial). 



mv Circular muscles of the veium. 



mw Circular muscles of the subumbrella. 



>i Urticating organs. 



nb Urticating swelling at the base of 



the tentacle. 

 nc Urticating ring of the umbrella margin. 



oh Auditory hairs (" setuke acusticse "). 

 ok Auditory clubs (cordyli). 

 ok, Larger perradial auditory clubs. 

 ok„ Smaller adradial clubs. 



Otolites. 



Otoporpse. 



Auditory pad in the peduncle of the 

 auditory club. 



Ectoderm. 



Ectoderm of the exumbrella. 



Ectoderm of the subumbrella. 



Nerves. 



Dorsal nerve ring. 



ol 

 oo 

 op 



1 



qe 

 qiv 



re 

 re 



so 



t 



tr 



u 



uf 



ug 



v 



ve 



Ventral nerve ring. 

 Ovaries. 

 Ess cells. 

 Tentacles. 



Tentacle root. 



Umbrella. 



Elastic fibres of the umbrella, 



Gelatinous substance of the umbrella. 



Velum. 



Exumbral epithelium of the velum. 

 vw Subumbral epithelium of the velum. 

 z Supporting (fulcrum). 

 zv Supporting plate of the velum. 

 zw Supporting plate of the subumbrella. 



Fig. 1. Ventral view of the entire Medusa (from below), with folded collar lobes and 

 tentacles, fifteen times the natural size. 



Fig. 2. Dorsal view of the entire Medusae., with collar lobes extended flatly, ten times 

 the natural size. 



Fig. 3. Profile view of the entire Medusa, with stiffly extended collar lobes and 

 extended oesophagus, fifteen times the natural size. 



Fig. 4. A collar lobe (or a quadrant of the umbrella collar), with the surrounding 

 parts, flatly extended, thirty times the natural size. 



Fig. 5. Horizontal transverse section through a peronial furrow, and the peronium 

 lying in it, greatly enlarged. 



Fig. 6. Radial section through a quadrant of the umbrella, projected semi-diagramati- 

 cally. twenty-five times the natural size. 



Fig. 7. Radial section through the umbrella margin and the auditory club with 

 peronium lying on it, greatly enlarged. 



Fig. 8. An auditory club, with the peronium belonging to it, and the surrounding 

 part of thr umbrella margin, greatly enlarged. 



