356 



MKI)US^3 OF THE WORLD. 



quite abundant at Naples upon the bottom in deep water in October and November, but 

 is not found in winter. Graeffe finds it at Rovingo and Piramo, Adriatic, from October to 

 February. For description, see the synoptic table of the species of Olindias. 



The red-colored "ocelli" described by Haeckel are actually excretion pores. According 

 to Stschelkanowzeff, the concretions are of entodermal origin and are innervated by the upper 

 nerve-ring. Crystals are found in the entoderm of the ring-canal. The large, oval nettle-cells 

 are associated each with a ganglion-cell, which sends out a network of fibers over the nettle- 

 cell. The nettle-cell is mounted upon 

 an elastic pad. The radial-canals are 

 entwined by a spiral (helical) entoder- 

 mal musculature. 



According to Bethe, 1903, if the 

 medusa be paralyzed by removing its 

 bell-margin, pulsations will recommence 

 if the bell be placed in pure NaCl. An 

 excess of 0.25 to 1 per cent of KG added 

 to the sea-water causes temporary pul- 

 sation in the paralyzed bell of Olindias, 

 but the final effect of potassium is 

 depressive, the initial stimulus being 

 only momentary. 



Bethe shows that in such medusae 

 as Olindias, Geryonia, Cotylorhiza, and 

 Rhizostoma, the pulsating tissue displays 

 a refractory period such as was demon- 

 strated by Marey, 1 876, in the vertebrate 

 heart. During the period of systole an 

 electrical stimulus has no effect, but only 

 during the period of diastole does such 

 a stimulus produce an extra contraction, 

 and the latent period preceding this extra contraction is shorter the later the stimulus is applied 

 in the diastolic phase. This applies to the medusae, however, only when at normal temper- 

 atures, for at temperatures much higher than the normal the medusa can be stimulated even 

 when in systole. 



Bethe shows that the refractory state is a property of the nerves, not of the muscles, for 

 the pulsation-stimulus is nervous in nature. On the other hand the latent period (1. e., the 

 time which elapses between the reception of the stimulus and the muscular contraction) is a 

 property of the muscles. 



Olindias malayensis Maas. 



Olindias phosphorica, Delle Chiaje; nov. var. malayensis, Maas, 1905, Craspedoten Medusen der Siboga Expedition, Monog. 

 10, p. 47, taf. 9, fign. 60, 61. 



The distinguishing characteristics of this form are its thick gelatinous walls, high, rounded 

 bell, and the thickly crowded, very elongate, club-shaped papillae of its gonads. The gonads 

 are mature when the medusa has fewer marginal appendages than 0. phosphorica of the Med- 

 iterranean or 0. sambaquiensis of the coast of Brazil. It is distinguished from O. tenuis of the 

 Bahamas and Florida by its numerous marginal clubs, which have swollen ends and narrow 

 necks. 



The disk is 25 to 35 mm. wide. 20 to 30 "primary" tentacles project out from the exum- 

 brella side of the margin; these have club-shaped outer ends and are provided with adhesive 

 disks as in Gonionemus; their shafts are covered with partial rings of nematocysts, which are 

 spaced at fairly regular intervals. These primary tentacles are relatively non-contractile and 

 are thicker than the secondary tentacles. A pair of lithocysts is found at the base of each of 

 the primary tentacles. These are inclosed in the gelatinous substance of the bell and each con- 

 tains a single, large, spherical concretion. The secondary tentacles arise from the lower side of 

 the bell-margin and are smaller and more contractile than the primary tentacles. There are 1 



Fig. 201 .—Olindias malayensis, after Maas, in Ergeb. Siboga Expedi 

 tion, Hvdromedusen. 



