The meaning of the letters 



aa Oral opening. 



ac Oral columns (interradial). 



nl Oral lobes. 



am Margin of the mouth. 



bb Buccal pouches (perradial). 



bp Perradial gastral pouches. 



bt Tentacular coronal pouches. 



ck Tentacular lobe canals. 



co Ocular canals (sense pouches). 



ec Coronal furrow of the exumbrella. 



ec' Thinnest part of the gelatinous substance 

 of the umbrella. 



cs Coronal sinus. 



ct Tentacle canals. 



ex Adocular canals. 



dg Endodermal surface of the stomach. 



er Marginal teeth of the umbrella disk. 



cs Marginal indentations of the umbrella disk. 



/ Gastral filaments. 



ga Buccal stomach. 



gb Basal stomach. 



gc Central stomach. 



gi Pyloric valves. 



go Gastral openings. 



gp Palatine opening. 



gw Swellings of the subumbral gastral wall. 



h Umbrella cavity. 



i Funnel cavities. 



is the same in all the figures. 



M Fused clasps. 



Id Cathammal plates (septal plates). 



I Marginal lobes. 



mc' Thinner inner coronal muscle. 



mc" Thicker outer coronal muscle. 



md' Perradial deltoid muscle. 



md" Interradial deltoid muscle. 



mk Root muscles of the tentacles. 



mt' Abaxial tentacle muscle. 



mt" Axial tentacle muscle. 



or Budimentary sense clubs. 



q Ectoderm. 



s Ovaries. 



sa Aperture of the genital sinus. 



so Ova. 



ss Genital sinus. 



st Fulcral frame of the sterigma. 



si Basal root of the sterigma. 



t Tentacles. 



uc Central umbrella disk. 



no Pedalia of the rhopalia. 



ut Pedalia of the tentacles. 



w Subumbrella. 



wr Mesenteries (perradial). 



yu Circular furrow on the subumbral wall of 



the coronal sinus. 

 zw Supporting plate of the subumbrella. 



Figs. 1 and 2 are natural size, the other figures twice the natural size. 



Fig. 1. — Exumbral view of the entire Medusa (from above), natural size. The deep coronal furrow 

 (ec) separates the indented umbrella margin (uc) from the corona of tentacle pedalia (ut) and sense 

 pedalia (uo). 



Fig. 2. — Subumbral view of the entire Medusa (from below), natural size. The eight ovaries (g) 

 lie in pairs round the stomach, whose eight mesenteries separate the four pairs. 



Fig. 3. — Subumbral view of the entire Medusa (from below), in four quadrants, twice the 

 natural size. The first quadrant (to the right, below) gives the complete subumbral view, whilst the 

 coronal muscle is removed in the three other quadrants. The corona of pouches is shown in the 

 second quadrant (to the left, below), the deltoid muscles and tentacle muscles in the third quadrant (to 

 the right, above). All the subumbral organs are removed in the fourth quadrant (to the left, above) to 

 show the endodermal surface of the gelatinous substance of the umbrella. A pair of the eight 

 genitalia is removed to the left above, a pair opened to the left below. The subumbral wall of the 

 stomach is complete only to the right below. 



Fig. 4. —Profile view of the entire Medusa, twice the natural size. The right half of the figure 

 shows the outer profile view, the left half, a radial section. 



Fig. 5.— Radial section through the oesophagus, twice the natural size, to show the swellings (gw) 

 and phacelli (f) on its inner wall. 



Fig. 0.— Horizontal section through the palatine opening (gp) or constricted middle of the 

 oesophagus, twice the natural size ; the triangular interradial cathammal plates Qc) project centri- 

 petally between the four perradial limbs of the cross. 



Figs. 7-8.— Two tangential sections through a tentacle root and the two adjacent rhopalar pedalia 

 (uo), twice the natural size ; fig. 7 further out, fig. 8 further in. 



Fig 9. — Eadial section through an ovary and the surrounding coronal sinus, twice the natural 

 size, showing the insertion of the sterigma (si) at the subumbral wall (w) of the coronal sinus (cs). 



