90 



MEDUS/E OF THE WORLD. 



separated in the 4 principal radii. The basal bulbs of the tentacles and the stomach are 

 brownish-red to bright crimson, and the entoderm of the tentacles is orange. 



This medusa is found off the Atlantic coasts of Western Europe, and in the Mediter- 

 ranean. Graeffe, 1884, states that at Trieste, Adriatic Sea, the medusae bud forth from the 

 hydroids in the spring, and a second brood appears to develop in summer. 



The hydroid is Gemmaria implexa, well described and figured by Allman, 1871-72. 

 The stems of the hydroid are erect, 6 to 8 mm. high, and arise at intervals from a creeping, 



net-like hydrorhiza which is attached to 

 shells, stones, etc., in shallow water. The 

 stems are usually single, but occasionally 

 they branch. The perisarc covers the 

 hydrorhiza and extends as a transversely 

 corrugated, opaque tube up the lower 

 part of each hydranth. Below the 

 zones of tentacles the perisarc becomes 

 abruptly smooth, and ends in a slightly 

 flaring cup. The hydranths are cylin- 

 drical to club-shaped, with dome-like 

 peristome. There are 40 to 50 short 

 tentacles, each ending in a knob of 

 nematocysts. These tentacles are ar- 

 ranged in 10 to 13 irregular verticils of 

 about 4 tentacles each, the tentacles 

 being about 90 apart. The medusa- 

 buds are borne upon peduncles which 

 arise in clusters from the sides of the 

 hydranth below the middle, but above 

 the lowermost verticils of tentacles. 



When set free the medusa has 2 

 well-developed tentacles which give 

 rise to numerous filaments, each ending 

 in a capsule bearing terminal bristles 

 and containing several nematocysts. 

 There are also 2 small tentacle-bulbs 

 90 apart from the well-developed ten- 

 tacles. The bell is oval and higher 

 than a hemisphere and 4 lines of 

 nematocysts extend up about one-fourth 

 to one-third of the bell-height, one above 

 each tentacle-bulb. The 4 radial-canals 

 are straight and simple, and the manu- 

 brium is a simple tube with a round 

 mouth-opening and straight cylindrical 



Fie. 43. Hydroid of Zanclea implexa, after Allman, in Ray sides. It lacks a peduncle and is about 



Society, 1871-72. See also, Fig. 44 . na lf as l on g as depth of bell-cavity. 



The hydranths are white with pale-pink entoderm. The perisarc on the proximal portion 

 of the hydrocaulus is brown and on the distal portion, colorless. It is closely related to the 

 hydroid of Zanclea gemmosa. 



Zanclea cladophora Hartlaub. 



Gemmaria cladophora, AGASSIZ, A., 1865, North Amer. Acal., p. 184, figs. 307-310. HAECKEL, 1879, Syst. der Medusen, p. 104. 

 NUTTING, 1901, Bull. U. S. Fish Commission for 1899, vol. 19, p. 371, fig. 78. HARGITT, 1904, Bull. U. S. Bureau of 



I-' i .lirrn-s, vol. 24, p. 42. 

 Zanclea cladophora, HARTLAUB, 1907, Nordisches Plankton, Nr. 12, p. 121, fign. 112-115. 



Bell pyriform and about as broad as high. Apical projection solid, rounded, and dome- 

 like. There are 2 long, diametrically opposed tentacles from the outer sides of which arise 

 a great number of slender filaments, each terminating in a knob-like body which contains 



