274 



MKDUSiE OF THE WORLD. 



Phialidium ambiguum. 

 Oceania ambigua, Agassiz, A., and Mayer, 1899, Bull. Mus. Comp. Zool. at Harvard College, vol. 32, p. 167, plate 6, figs. 18, 19. 



Bell pyriform, and 4 mm. in diameter. Gelatinous substance very thick. There are 16 

 short tentacles with large basal bulbs; 1 or 2 lithocysts between each successive pair of ten- 

 tacles. Each lithocyst contains a single spherical concretion. Velum well-developed. 4 

 straight, moderately wide radial-canals. The immature gonads are situated upon these canals 

 near the manubrium. Manubrium flask-shaped, 4 simple lips. 



Entodermal axis of each tentacle brown; ectoderm of stomach, gonads, and tentacles, 

 green. 



Single specimen found at Suva, Fiji Islands, South Pacific, January 4, 1898. Distin- 

 guished by its veryjrhick, pyriform bell. 



Phialidium brunescens, described by Bigelow from the Maldive Islands, is closely related 

 to this medusa, but is distinguished by its flat bell, thin walls, and the large size of the gonads 

 in medusa smaller than P. ambiguum with small gonads. In both forms tentacle-bulbs 

 are brown, but they appear to be much darker in P. brunescens. 



147- 



Fir,. 147.— Phialidium iridescens, after Maas, in Voyage 



S. Y. Belgica. 

 Fir.. 148.— Phialidium brunescens, after Bigelow, in Bull. 



Museum Comp. Zool. at Harvard College. 



Phialidium brunescens. 

 Oceania brunescens, Bigelow, 1904, Bull. Mus. Comp. Zool. at Harvard College, vol. 39, p. 253, plate I, fig. 2. 



Bell flat, 2 mm. wide, 0.7 mm. high. About 30 short, thick tentacles with swollen bases. 

 No tentacular knobs on the margin. 32 to 40 small lithocysts each with 1 or 2 concretions. 

 Manubrium very short and broad, with 4 simple lips. The gonads are the most distinctive 

 feature of this medusa, and are large, thick, and prominent, and occur on the proximal thirds 

 of the 4 radial-canals. Bell colorless. Radial-canals and gonads greenish-yellow. Tentacles 

 colorless, but with a prominent, brown pigment-spot at the base of each. Maldive Islands, 

 Indian Ocean, in January. Distinguished by its swollen tentacle-bulbs, large hemispherical 

 gonads, and flat hell with relatively thin walls. The nearly allied P. ambiguum of the Fiji 

 Islands has a high, thick-walled, pyriform bell. 



Phialidium simplex Browne. 



Phialidium simplex, Browne, 1902, Annals and Mag. Nat. Hist., ser. 7, vol. 9, p. 282; 1908, Trans. Roy. Soc. Edinburgh, vol. 

 46, p. 236. 



Bell watch-glass-shaped, 22 mm. wide, 10 mm. high. 60 to 85 tentacles and a few rudi- 

 mentary tentacle-bulbs. 60 to 85 or more lithocysts alternating with the tentacles. A single 

 concretion in each lithocyst. Stomach short with 4 perradial lobes. Mouth with 4 large fim- 

 briated lips. Gonads extend over outer halves of the radial-canals and almost reach the ring- 

 canal. They areslightly folded. Common at Stanley Harbor.Falkland Islands, from November 

 to February. 



Genus PHIALUCIUM Maas, 1905. 



Phialutium, Maas, 1905, Craspedoten Medusen der Siboga Expedition, Monog. 10, p. 32; 1906, Revue Suisse de Zool., tome 14, 

 p. 92. -Bigelow, H.B., 1909, Mem. Comp. Zool. at Harvard College, vol. 37, p. 157. 



Maas established the above as a subgenus of Phialidium. Phialucium resembles Plnali- 

 dium, but has permanently rudimentary tentacle-bulbs upon the bell-margin. The stomach 

 lacks a well-developed peduncle. The lithocysts may contain one or more concretions. 



