CIIIROPSALMUS BUITENDIJKI. 103 



The sense-orgaus (rhopalia), situated at a short 

 distance above the margin of the bell, lie protected in an 

 ellipsoidal niche of the exumbrella, under a hood-like pro- 

 jection of its upper margin (figs. 1, 2, sn and fig. 3); the 

 longest axis of the niche measures 5 mm., the shortest 

 one 2 mm, in length. Each organ (fig. 5) consists of a 

 hollow stalk and a retort-shaped swelling, that at its 

 inferior part bears a sac, wherein are contained the sta- 

 toliths; I could not recognize these concretions, probably 

 they were dissolved by the action of the formaline. Along 

 its median border the sensory club bears two complicated, 

 unpaired eyes, a large one and a smaller one above it, 

 both provided with a lens and pigmented cup ; moreover 

 on each side of the club there lies a pair of small, simple 

 eye-spots. 



The opening of the bell- cavity is surrounded by a 

 velarium (fig. 1, ve), suspended by the four frenula (fig. 

 2, fr); its breadth measures about a third of the height 

 of the bell. The diverticula of the gastro- vascular system, 

 contained in it, are much branched. Each quadrant of the 

 velarium possesses four of these canals of different shape 

 (fig. 6, vc). The diverticulum, situated next to the frenulum, 

 extends till the margin of the velarium and bears only along 

 its outer border some large dendritical canals, shaped like a 

 coral-tree ; that situated next to the pedalium is in its origin 

 much broader than the foregoing, but already in the middle 

 of the velarium it divides into a great number of branches. 

 Above, the bell-cavity is roofed over by the stomach 

 (fig. 2, St), having about the shape of a saucer; it com- 

 municates with the stomach-pockets in the lateral sides of 

 the bell by means of the four gastric ostia (figs. 1 and 2, 

 go), that are seen in a side-view of the medusa like a 

 small circular area, lying between two larger ones (the 

 bases of the pocket-arms). Each ostium is guarded by a 

 kind of valve, consisting of a knob-like protuberance of 

 the exumbrella. Like as in Chiropsalmus quadrumanus the 

 phacelli (fig. 2, ph) are placed in a horse-shoe-shaped 



Notes from the Leyden JMuseum, Vol. XXIX. 



