42 MEDUSAE OF THE WORLD. 



and is surrounded by a couple of rows of numerous irregularly arranged tentacles. These 

 oral tentacles are highly contractile, and are much smaller than those at the lower base of the 

 polypite. The medusae are borne upon branched stolon-like diverticula of the side walls of 

 the polypite, immediately above the zone of basal tentacles. Fully-developed medusae have 

 not been seen to be set free from the hydroid, but the similarity of the most advanced medusa- 

 buds observed to the free medusa found in the ocean leaves but little doubt concerning this 

 point. May, 1903, has studied the histology and embryology, and concludes that the medusa- 

 buds may at times become free, but usually mature while still attached to the hydranth. 

 This species has been found from Vineyard Sound to the mouth of the St. Lawrence River. 

 The medusa appears upon the southern New England coast in April and May, but is not seen 

 during the summer months, although the hydroid is abundant at this time. 



It is possible that Euphysa tentaculata Linko, 1905, is identical with H. pendula (see 

 Zool. Anzeiger, Bd. 28, p. 214). Linko's medusa is from Barents Sea, north of Russia. I 

 have referred to this medusa in the description of Steenstrupia bigelowt. 



Hybocodon forbesii Mayer. 

 Plate I, fig. 8; plate 2, fig. 3. 



Hybocodon jorbesii, MAVF.R, 1894, Bull. Mus. Comp. Zool. at Harvard College, vol. 25, No. II, p. 236, plate I, fig. l; 1904, 

 Memoirs Nat. Sci. Museum Brooklyn Institute, vol. i, No. i, p. 8, plate 2, fig. 13. 



Medusa. Bell asymmetrical, about 2.5 mm. in height and ellipsoidal in shape, being 

 slightly higher than broad. The gelatinous substance is of uniform thinness. There is a 

 single well-developed tentacle situated at the base of the longest radial-canal. A short, conical 

 tentacle is found at the base of the shortest radial-canal, and two smaller tentacle-bulbs are 

 situated one at the base of each of the intermediate canals. The well-developed tentacle is 

 about as long as the bell-diameter. Its base is small, and hardly greater in diameter than 

 the shaft of the tentacle. Its free extremity is fusiform, and covered with prominent nemato- 

 cyst-cells. No medusa-buds have ever been observed. The velum is narrow. The 4 radial- 

 canals are straight and slender and the circular canal is narrow. There are no rows or clusters 

 of nematocysts upon the exumbrella. Manubrium is spindle-shaped and swollen, and the 

 mouth is a simple, round opening situated at the extremity of a narrow tubular neck, which 

 extends beyond the velar opening. The entoderm of the terminal swelling of the large ten- 

 tacle is yellow streaked with red. Entoderm of manubrium yellow with red flecks. 



This species is found in Nassau Harbor, New Providence Island, Bahamas, and at 

 Tortugas, Florida, in March to May. It is an abundant surface form. I have captured 

 many hundreds of specimens, but have never found them producing either medusa-buds or 

 actinula larvae. It is distinguished by its decided yellow and orange color, and the absence 

 of meridional lines of nettle-cells over the exumbrella. 



"Hybocodon unicus." 



Amphicodon unicus, BROWNE, 1902, Annals and Mag. Nat. Hist., ser. 7, vol. 9, p. 276. 



(?) Hybocodon chilensis (hydroid), HARTLAUB, 1905, Zoolog. Jahrbuchern, Suppl. 6, p. 545, fig. W. 



Bell 3 mm. high, 2 mm. wide, bell-shaped. I solitary tentacle between 2 rudimentary 

 basal bulbs; 3 perradially situated bulbs without tentacles. Medusa-buds ( ?) Manubrium 

 cylindrical, nearly as long as the umbrella cavity. Color ( ?) Asymmetry of bell ( ?) One 

 specimen was found by Vallentin, and briefly mentioned without figures by Browne, from 

 Stanley Harbor, Falkland Islands. Hybocodon chilensis Hartlaub, from the coast of Chile, 

 may prove to be the hydroid of this medusa ( ?) It will be impossible to identify the medusa 

 from the brief mention of it given by Browne, unless, indeed, it be rediscovered in Stanley 

 Harbor. 



Hybocodon chilensis Hartlaub. 



Hybocodon chilensis, HARTLAUB, 1905, Zoolog. Jahrbuchern, Suppl. 6, p. 545, fig. W. 



(?) Amphicodon unicus (medusa), BROWNE, 1902, Annals and Mag. Nat. Hist., ser. 7, vol. 9, p. 276. 



(?) Steenstrupia occidentalis (medusa), FEWKES, 1889, Bulletin Essex Institute, Salem, vol. 21, No. 7, p. 107, plate 3, fig. I. 



Hybocodon occidenlalis, HARTLAUB, 1905, Zoolog. Jahrbuchern, Suppl. 6, p. 545. 



As Hartlaub states, this hydroid may be the stock of Amphicodon (Hybocodon) unicus 

 Browne, from the Falkland Islands. 



