The letters have the same meaning in all the figures. 



a Oral opening (fused). 



ah Oral arms. 



ah Oral disk (brachial disk). 



an Funnel frills (sucking frills). 



ao Frill mouths (sucking mouths). 



ap Brachial pillars (oral pillars). 



as Oral cross (fused). 



ca Adradial subumbral canal. 



cc Circular canal. 



cd Pillar canals (perradial). 



ch Brachial canals (adradial). 



ci Interraclial subumbral canals. 



cp Perradial subumbral canals. 



cv Velar canals (lobe canals). 



ga Buccal stomach. 



gc Central stomach. 



gg Gastrogcnital membrane. 



gh Cross of the gastrogenital membrane. 



gm Margin of the central stomach. 



ig Subgenital openings (portale). 



ir Subgenital porticus. 



lo Ocular lobes. 



Iv Velar lobes. 



1 Perradial rhopalia. 



2 Interraclial rhopalia. 

 g Genitalia (genital frills). 

 gx Distal ends of the genitalia. 

 ug Gelatinous substance of the umbrella. 

 w Subumbrella. 

 2 Supporting plate (fultura). 



With exception of figs. 5 and 8 all the figures are drawn in natural size. 



Fig. 1. — The entire Medusa, profile view (from the side), natural size. To the right, 

 an octant of the velarium is cut away, to show a subgenital ostium (ig), bounded on 

 either side by an oral pillar (ap). 



Fig. 2. — Radial section through the entire Medusa, natural size. The umbrella is 

 only connected with the brachiferous disk (ah) by the perradial oral pillars (ap). The 

 central stomach (gc), from which the radial canals run out, is also only connected by the 

 four pillar canals (cd), with the buccal stomach (ga) from which the eight brachial canals 

 diverge. 



Fig. 3. — The entire Medusa, exumbral view, from above, natural size. The cruciate 

 central stomach, with the genital cross, shines through the umbrella, 'which appears divided 

 into polygonal areee ; twice the natural size. The eight sense clubs are visible on the 



margin. 



Fig. 4. — The entire Medusa, subumbral view (from below), natural size. The four 

 perradial oral pillars (ap) are cut away at the base and removed along with the pendant 

 oral disk, and the eight arms, so as to show the whole subumbral surface freely ; in the 

 middle the cruciate gastrogenital membrane (which forms the fundus of the central 

 stomach). 



Fig. 5. — Rosette of tufts of the oral disk, in the middle of its ventral surface, from 

 below ; twice the natural size ; the eight adradial limbs of the disk hang in pairs from 

 its base. 



Fig. 6. — The dorsal surface of the oral disk, from above, natural size ; the buccal 

 stomach (ga) shines through in the middle. Sections through the four pillar canals (cd) 

 are shown at the four perradial angles, with the distal end of the genitaba (gx) on 

 either side. 



Fig. 7. — The ventral surface of the oral disk, from below, natural size. Three of the 

 four pair of arms are cut away at the base ; the rosette of tufts in the middle is removed, 

 to show the fused suture of the oral cross (ao). 



Fig. 8. — Transverse section through an arm, at the beginning of the formation of 

 the frills, slightly enlarged. an 1 Ventral (unpaired) frill. an 2 Dorsal (paired) frills, 

 c/ij Ventral (unpaired) brachial canal. ch 2 Dorsal (paired) brachial canals. 



