58 



MEDUSJE OF THE WORLD. 



except at its base, and is quite smooth. The polypites are very elongate, spindle-shaped, 

 and have about 1 6 to 24 short, knobbed tentacles arranged in 4 to 6 somewhat irregular 

 verticils. The medusa-buds arise singly upon short peduncles near the bases of the tentacles 

 of the lower verticils. The entoderm is red to reddish-brown and the stems are yellow. 



Browne found that confinement in an aquarium under somewhat unnatural conditions 

 caused the hydroid to grow rapidly and to form stolons, these being developed from branches 



which touched the glass sides of the aquarium. 

 He also discovered that the medusa becomes 

 mature in from J to 10 days after being set free 

 from the hydroid. Later, in 1907, Browne found 

 that one of these hydroids placed in a glass tube 

 with a constant current of water passing through 

 it grew in length from 14 to 77 mm. in the course 

 of 9 days, and developed branches having a total 

 length of 500 mm. The hydroid was fed upon 

 copepods. 



Sarsia radiata von Lendenfeld. 



Sarsia radiata, VON LENDENFELD, 1884, Zool. Anzeiger, Jahrg. 7, 

 p. 584; 1884, Proc. Linnean Soc. New South Wales, vol. 

 9, pp. 583, 635; plate 20, figs. 31, 32; plate 30, figs. 1-4. 



Medusa. Bell semiovate, slightly higher 

 than broad, 3 mm. high, 2.5 mm. wide. 4 ten- 

 tacles, each about 1.5 times as long as bell-height, 

 and with large bulbs about half as wide as the 

 manubrium. Ocelli (?) Velum wide. 4 straight 

 radial-canals. Manubrium cylindrical, half as 

 long as the bell-height. The gonad incases the 

 sides of the manubrium from the inner apex of 

 the bell-cavity to near the mouth. No medusa- 

 buds. Entoderm of manubrium and tentacle- 

 bulbs deep brown. Other parts colorless. 



H \droid. The hydrocauli arise from a 

 creeping hydrorhiza which anastomoses in a 

 very open network. The perisarc terminates 

 with an oblique elliptical margin at the base 

 of each hydranth, and the hydranth is provided 

 with a muscle at this point which enables it to 

 bend downward and "shut up" as if it were the 

 blade of a penknife. The hydranths are spindle- 

 shaped, narrow, and elongate; and are, includ- 

 ing their hydrocauli, 3 to 5 mm. high. They have 6 to 8 verticils, each of 4 tentacles, situated 

 in 4 meridional lines, 90 apart. These tentacles are all knobbed at their ends. The hydranths 

 which produce medusae are shorter than the sterile polypites. The medusae bud out from the 

 lower half of the polypite between the tentacles. The entoderm is intensely brown in color, 

 and the perisarc is bright brownish-yellow. Other parts colorless. Found on the coast of 

 New South Wales, Australia. The medusae are produced in April and May. 



Sarsia conica. 

 Codonium eonicum, HAECKEI., 1880, Syst. der Medusen, p. 634. 



Bell barrel-shaped with conical apex one-third as long as the sides of bell. 12 mm. high, 

 4 mm. wide. 4 tentacles longer than bell-height, and with small oval basal bulbs. The 

 manubrium is half as long as the depth of the bell-cavity. The stomach is subspherical and 

 swollen by the encircling gonad. The mouth is at the end of a short, cylindrical throat-tube 

 which is free of gonads. Color ( ?) There is a long axial canal above the stomach. Indian 

 Ocean. Briefly described, without figures, by Haeckel. 



FIG. 21. Sarsia eximia, from life, by the author. Mouse- 

 hole, Cornwall, England, Nov. 14, 1907. 



