REPOKT ON THE DEEP-SEA MEDUSAE. 71 



line of the pyloric opening (gy, figs. 12, 13), into two distinct sections of equal height, 

 a lower distal half, and an upper proximal half. The lower or distal half of the funnel 

 (or the " central funnel," fig. 16, 17, ic) lies in the outer surface of the central stomach (gc) ; 

 its inner or axial wall is formed by the obelisk plates (yz) of the central stomach, its outer 

 or abaxial wall by the subumbral wall of the coronal sinus (cs). The upper or proximal 

 half of the funnel (or of the " basal funnel," fig. 14, ib) is encircled by the four niches of the 

 basal stomach (gn), and is only joined to the inner wall of the gelatinous umbrella at the 

 interradial line (fig. 14, ug). The four funnel cavities of the Peromedusas are homologous 

 with those of the Stauromedusaa and the Cubomedusas, and may also be comparable to the 

 subgenital cavities of the Discomedusas, the respiratory cavities of older authors on the 

 medusas. In fact, they may serve both as means of respiration and locomotion, as they 

 are emptied by each systole of the umbrella and filled with fresh water by each diastole ; 

 their wall is firm, but very thin. 



The inner concave umbrella wall or subumbrella, shows a highly developed system 

 of strong swimming muscles, evolved from the more simple muscles, which I distinguished 

 in the Stauromedusee as the distal coronal muscle and the proximal bell muscle (comp. my 

 System der Medusas, 1879, pp. 366, 382, 399, 456, taf. xxi. xxx., &c). The coronal 

 muscle ("musculus coronaris," mc) is improved into a powerful broad band, and more 

 strongly developed than in all other Acraspedse. It consists of powerful leaves of the 

 circular muscle, whose thick supporting plate rises above the subumbral surface in the form 

 of 10 to 12 strong circular folds ; the height of these circular folds (?nc 2 ) decreases from 

 above to below, their breadth increases (PI. XIX. fig. 6 ; PI. XXI. fig. 8 ; PL XXII. fig. 22,mc). 

 The upper or proximal margin of the coronal muscle (figs. 8, 22, mc-i) forms a simple cir- 

 cular line, corresponding with the distal margin of the large circular sinus. The lower or 

 distal margin of the coronal muscle (figs. 8, 22, mc 4 ) forms sixteen triangular, subradially 

 projecting points which run as far as the middle of the marginal lobes. The whole 

 coronal muscle is therefore divided by sixteen selvages into sixteen quadrangular area?, 

 the coronal plates ("tabulae coronares"). The four interradial ("ocular") are some- 

 what narrower than the remaining twelve (" tentacular "). They are divided by the lobe 

 clasps (" loboporpss," M), the longitudinal fused selvages, which divides each marginal 

 lobe into two halves (comp. pp. 66, 67) ; they serve at the same time as firm cartilage- 

 bke selvages for the insertion of the circular muscular fibres. Each quadrangular coronal 

 plate corresponds, therefore, to the adjacent halves of two marginal lobes, and connects 

 them most closely. Four of the muscular areas correspond at the same time to the four 

 interradial sense clubs, whilst the twelve others correspond to the tentacles. The two 

 lateral margins of each muscular area (formed by the lobe clasps) are straight, and con- 

 verge upwards ; the lower or distal margin is the larger, and sinuated concavely ; the 

 upper or proximal margin is convex, and touches alternately the basis of the deltoid 

 muscles and the distal end of the genitalia. 



