308 MEDUS/E OF THK WORLD. 



These structures develop, however, at a later period. As the medusa develops, the peduncle 

 appears and increases in size, the tentacles increase in number, and the lithocysts develop. 

 This species has been found by McCrady, 1857, in Charleston Harbor, and by Brooks, 

 1883, at Beaufort, North Carolina. Our description of the hydroid and young medusa is 

 taken from that of Brooks, 1883 (pp. 470 to 473). Unfortunately the medusa has never been 

 figured. It appears to be distinguished from P. pyramidalis by its high bell, few tentacles, 

 reddish color, and large stomach. 



Phortis pyramidalis Mayer. 

 Plate 39, figs. 3-6. 



Eutima pyramidalis, Agassiz, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 363.— Agassiz, A., 1865, North Amer. Acal., p. 118.— 



Haeckel, 1879, Syst. der Medusen, p. 191. 

 Phortis pyramidalis, Mayer, 1900, Bull. Museum Comp. Zool.at Harvard College, vol. 37, p. 59, plate 10, figs. II, lla; 1904, 



MemoirsNat. Sci. Museum Brooklyn Institute Arts and Sci., vol. 1, p. 17, plate 3, fig. 25. 



Adult medusa (plate 39, fig. 5).— Bell slightly flatter than a hemisphere and attains a 

 diameter of about 35 mm. There are about 100 small, slender tentacles, which lack lateral or 

 marginal cirri. About 100 lithocysts alternate with the equally numerous tentacles. Each litho- 

 cyst contains a single spherical concretion. There are 4 narrow radial-canals. The very small 

 stomach is mounted upon a wide, cone-shaped, gelatinous peduncle which fills most of the 

 cavity of the bell and projects outward for a considerable distance beyond the velar opening. 

 The stomach is provided with 4 delicate, crenated lips. The 4 gonads are linear and devel- 

 oped upon the outer parts of the 4 radial-canals near the circular canal. 



The stomach, tentacle-bulbs, and gonads are of a delicate blue-green color. 



This medusa is very abundant among the Bahamas and Tortugas Islands, and off" the 

 Florida coast. At night, when disturbed, it glows with an intense blue-green phosphorescence, 

 far more brilliant than that of any other medusa we have observed. 



Young medusa.— In the youngest medusa observed (plate 39, fig. 3) the bell was higher 

 than a hemisphere and 3 mm. in diameter. There was no peduncle and the gelatinous sub- 

 stance was not very thick. There were 4 slender radial tubes and 16 tentacles, only 8 ot 

 which had attained to any considerable length, the others being mere basal bulbs. There 

 were about 8 lithocysts, each containing a single spherical concretion. 



When the medusa is about 7 mm. in diameter (plate 39, fig. 4) the bell is flatter than a 

 hemisphere. The peduncle is well developed and extends beyond the velar opening. The 

 stomach has grown very little and is, relatively to the size of the medusa, much smaller than in 

 the younger animal. There are 4 recurved lips. There are now about 32 tentacles and 16 

 lithocysts. Hydroid unknown. 



Phortis lactea Mayer. 

 Plate 40, fig. 2; plate 41, fig. 6. 

 Phortis lactea, Mayer, 1900, Bull. Museum Comp. Zool. at Harvard College, vol. 37, p. 58, plate 40, fig. 133. 



Bell is 5 mm. in diameter and sides flange slightly outward at margin. The gelatinous 

 substance is of moderate thickness at the aboral pole, but becomes thin at margin ot bell. 

 There are about 18 to 22 short, simple tentacles, the basal bulbs of which are large and swollen. 

 These tentacles are only about one-fifth as long as the bell-diameter. There are neither 

 lateral nor marginal cirri. The lithocysts are slightly more numerous than the tentacles, there 

 being at least 1, and occasionally 2, of these structures between each successive pair ot ten- 

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

 are 4 straight, slender radial-canals, which extend down the peduncle to the stomach. The 

 peduncle is wide at its base, but not so wide as in Phortis pyramidalis. It extends for a 

 short distance beyond the velar opening of the bell. The stomach is cruciform in cross-section, 

 and there are 4 simple recurved lips. The 4 gonads are situated upon the 4 radial-canals, a 

 short distance above their junction with the circular vessel. Each gonad is linear, and in the 

 female the ova are quite conspicuous. 



The gonads and stomach are milky in color, while the tentacle-bulbs are cream-colored 

 with greenish or faint salmon-colored entodermal granules. 



Found at the Tortugas, Florida, in June and July. The hydroid is unknown. 



