Fjo-. l. — The entire Medusa, five times the natural size, seen from the side. The 

 louo- quadrangularly prismatic oesophagus, which is circularly constricted above the oral 

 opening, projects in the middle far out from the opening of the umbrella cavity. The 

 oesophagus is surrounded by the numerous branches of the four powerful, dichotomously 

 branched, blood-red oral styles, whose terminal branches bear an urticating knob. The 

 four leaf-shaped, pinnated genitalia are seen above the oral styles in the side walls of 

 the inverted pyramidal central stomach. The four narrow radial canals run out from 

 the base of the central stomach and are united into a coronal canal at the umbrella 

 margin above the pigmented urticating ring. A pigmented ocellar bulb lies below its 

 opening. Two long tentacles, furnished with urticating rings, run out from two opposite 

 bulbs. 



Fig. 2. — Umbrella seen from above, four times the natural size. gc Central 

 stomach. 6" Genitalia (ovaria). gx Interradial furrow of the gastral wall, cr Radial 

 canals, cc Coronal canals, mi Interradial longitudinal muscles of the sub umbrella. 

 v Velum, ug Gelatinous substance of the umbrella, ne Urticating knobs of the 

 umbrella. 



Fig. 3. — The central stomach, seen from below, eight times the natural size, with 

 the oesophagus (at) and the four oral styles (ay) cut off at their bases. The four leaf- 

 shaped, pinnated genitalia (sf) cover the greater part of the wall of the stomach (gc). 

 Four perradial internal gastral grooves (gs) alternating with four interradial external 

 gastral furrows (gx). 



Fig. 4. — The oral opening and the lowest part of the oesophagus surrounding it, seen 

 from below ten times the natural size, ar Four perradial oral grooves (on the inner side 

 of the ribs of the oesophagus which project outwards), ma Urticating knobs of the oral 

 margin, ax Axial hollow space of the oesophagus. 



Fig. 5. — Four terminal branches of an oral style, greatly enlarged, with their 

 terminal urticating knobs, (d) Coin-shaped chordal cells of the solid endodertnal axis, 

 with then central nuclei, (z) Internal plate or supporting lamella, (m) Muscular plate. 

 (g) Ectoderm, fn Terminal urticating knob. 



Fig. 6. — A genitalium shaped like a pinnated leaf, whose perradial midrib forms both 

 a gastral rib and the gastral groove running in it. 



Fig. 7. — Branch of an oral style in transverse section, greatly enlarged, d An 

 endodermal chordal cell with its nucleus y, surrounded by branched filaments of proto- 

 plasm, which are united into a thin layer of protoplasm both inside round the nucleus, 

 and outside on the inner wall of the cell, z The supporting lamella belonging to the 

 cell, m Muscular plate (longitudinal muscular fibrillar in transverse section), q Ecto- 

 dermal epithelium. 



Fig. 8. — A mature ovum, with large clear germinal vesicle and dark double-contoured 

 germinal spot. 



