TRACHYMEDUS.E — OLINDIAS. 355 



gelatinous substance of the bell. The lithocysts flank the sides of" these radial-canals and 

 diverticula. The 4 gonads are papilliform and reflected from side to side, and are developed 

 upon the outer halves of the 4 radial-canals (plate 48, fig. 7). Manubrium tubular, cruci- 

 form in cross-section and elongate, with 4 recurved lips; it extends about three-quarters of 

 the distance from inner center of bell-cavity to velar opening. 



The gelatinous substance of the bell is of a delicate greenish-yellow. The entoderm of 

 the manubrium, gonads, and tentacle-bulbs is opaque yellow-green, with the innermost parts 

 purple. There are 4 interradial, reddish-purple pigment-spots upon the manubrium near 

 the points of origin of the radial-canals. The nematocyst-warts upon the short, exumbrella 

 tentacles are either white or dark-purple, while the half-rings on the long, flexible, marginal 

 tentacles are red and yellow. 



Development of medusa (plate 47, figs. 8 to 10). — The youngest medusae observed were 

 about 0.7 mm. in diameter, the bell being higher than a hemisphere and the exumbrella 

 surface regularly besprinkled with nematocysts. There were 8 tentacles, 4 radial and 4 inter- 

 radial, all belonging to the short, straight, exumbrella set and projecting from sides ot bell 

 above bell-margin. Only 4 lithocysts, one at base of each interradial tentacle. Radial-canals 

 narrow and straight-edged; the circular vessel simple, without centripetal diverticula. Manu- 

 brium quadratic and very short. 



As the medusa grows, its bell increases in height relatively faster than in width, so that 

 it becomes higher than a hemisphere and resembles in shape the bell of Bougamvillia. When 

 3 mm. high there are still only 8 tentacles, but the radial-canals have become broad with 

 serrate edges and 4 interradial diverticula begin to develop from the circular vessel. The 8 

 tentacles have greatly elongated and terminate in simple nematocyst-knobs. When the medusa 

 is 8 mm. in diameter 16 of the tentacles project from the sides of the bell and about an equal 

 number of the flexible, coiled tentacles arise from the bell-margin. 32 lithocysts, a pair on 

 inner side, above the velum and flanking each of the 16 tentacles arising from sides of bell. 

 There are now 3 blindly ending, centripetal canals that arise from the ring-canal in each 

 quadrant. The gonads have not yet made their appearance. The tentacles that arise from 

 the sides of the bell have begun to develop their peculiar pad-like disks upon their aboral 

 sides. These pad-like disks, which are evidently homologous with the adhesive disks in 

 Gonionemus and Cubaia, are developed from the aboral side of the primitive nematocyst-knobs 

 of the tentacles, as is shown in successive stages represented in plate 48, figs. 2 to 4. We see, 

 then, that the youngest medusa of Olindias may be said to be in the "Gonionemus stage," 

 for it has only tentacles of the exumbrella set and the circular canal is simple and without 

 diverticula. It seems probable, therefore, that Olindias is descended from a Gonionemus-like 

 medusa. The stiff, exumbrella tentacles are therefore primitive, while the flexible marginal 

 tentacles are secondary. 



Olindias tenuis is one of the few medusae that thrive best on the shallow flats of the 

 Bahamas, Bermudas (Bigelow), and Florida coast, and is very abundant during the sum- 

 mer months in Nassau Harbor, and at Key West, Florida. It appears to become mature 

 with fewer centripetal canals and tentacles, and when of smaller size than 0. sambaquiensis 

 of Brazil. We must bear in mind, however, that it may be only a small northern variety 

 of 0. sambaquiensis. 



Bigelow, 1909, gives the best modern description of this medusa. 



Olindias phosphorica Haeckel. 



Oceania phosphorica, Delle Chiaje, 1841, Mem. sulla storia degli animali senza vertebrati, Napoli, tome 5, p. 131, plate 147, 

 figs. 1-3. 



Thaumantias punctata, Sfagnolini, 1876, Catalogo Acalefi Mediterraneo, p. 26, tav. 4, fig. I. 



Olindias phosphorica, Haeckel, 1880, Syst. der Medusen, p. 654; Ibid., 1879, p. 253, taf. 15, figs. 9-13 (Olindias mtilleri).— 

 Maas, 1905, Craspedoten Medusen der Siboga Expedition, Monog. 10, p. 48. 



Olindias mulleri, Graeffe, 1884, Arbeit. Zool. Inst. Wien, Bd. 5, p. 359.— Goto, 1903, Mark Anniversary Volume, p. 14.— 

 Browne, 1904, Fauna and Geog. Maldive and Laccadive Archipelagoes, vol. 2, p. 737.— Bethe, 1903, Allgemeine 

 Anatomie und Physiol. Nervensystem, p. 419 (effects of chemicals on pulsation)— Stschelkanowzeff, 1905, Nachricht. 

 Gesell. Freunde Natur. Moskau, Bd. no, p. 42, taf. 45, fign. 1-31; 1906, Zoolog. Centralblatt, Bd. 13, p. 679 (anatomy 

 and histology). — Bigelow, H. B., 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 109. 



This species is found in the Mediterranean. It is best described by Haeckel, Bigelow, 

 and Goto. Delle Chiaje and Haeckel present good figures of the medusa. It is sometimes 



