ANTHOMEDUS.E TRICHORHIZA, STEENSTRUPIA. 



29 



Trichorhiza brunnea Russell. 



Trichorhiza brunnta, RUSSKLL, 1906, Proc. Zool. Soc. London, p. 99, plate 5, figs. 1-2; Abstract, Pruc. Zool. Soc. London, 

 No. 26, p. 6, Feb. 13, 1906. 



Mature medusa unknown. When newly set free from the hydroid the medusa is pyriform, 

 with a thin-walled bell, well-developed velum, and 4 rudimentary tentacle-bulbs, one of 

 which is larger than the others. The manubrium when extended is as long as the depth of 

 the bell-cavity, and it is cylindrical, narrow, and provided with a simple, circular mouth- 

 opening which is surrounded by nematocysts. There are 4 simple, straight radial-canals, 

 but no gonads. The manubrium and tentacle-bulbs are yellow, the former being faint and 

 the latter golden in color. 



This medusa is liberated by a solitary hydroid which was found on June 29, 1905, at a 

 depth of 17 fathoms in Ethick Bay, Bute, Firth of Clyde, Scotland. The hydrorhiza of the 



Trichorhiza was entwined among and 

 around the tentacles of Coryrnorpha 

 nutans. The hydroid is 1 1 mm. in total 

 length, the hydranth itself being only 

 1.5 mm. long. The hydrorhiza is long, 

 filiform, and sparingly branched, with 

 about 6 simple branches which arise 

 from its lower (aboral) half. The 

 coenosarc does not appear to extend 

 over this branched lower half of the 

 hydrorhiza. Above the upper end of 

 the hydrorhiza the perisarc extends to 

 form a cup-like hydrotheca, which 

 bears 4 transverse grooves. Immedi- 

 ately below this hydrotheca the peri- 

 sarc displays several longitudinal lines. 

 Hydranth conical, 1.5 mm. long and 

 0.8 mm. wide, with an oral circlet of 7 

 very short tentacles having knob- 

 shaped ends. There is also a basal 

 circlet of 12 filiform tentacles, which 

 are ringed with nematocysts and are 

 tapering, and fully as long as the hy- 

 dranth itself. 8 or 10 medusa-buds 

 arise at various levels from the sides 

 of the polypite between the basal and 

 oral circlets of tentacles. 



The perisarc of the hydrorhiza is 

 straw-colored, and that ot the hydro- 

 theca chocolate-colored. Body of hy- 

 dranth pale reddish-brown, tentacles 

 translucent white. 



This hydroid bears some resemblance to Blastothela of Verrill, 1878. Amer. Jour. Sci., 

 ser. 3, vol. 1 6, p. 374. 



FK.. 3. Trichorhiza brunnea, after Russell, Proc. Zool. Soc., London, 1900. 

 Hydroid, and enlarged view of recently liberated medusa. 



Genus STEENSTRUPIA Forbes, 1846. 



Sleenslrufia, FOR BBS, 1846, Annals and Mag. Nat. Hist., vol. 1 8, p. 287. LKI:CKART, 1856, Archiv. fiir Naturgesch., Bd.22, p. 29. 

 Slrrnstrupia + Euf>h\!a, HAF.CKEL, 1879, Syst. der Mcdusen, pp. 29, 3 i . BROWN t, 1895, Trans. Liverpool Biol. Association, 



vol. 9, pp. 247, 248. 

 Eu/ihysa Sticnitrufia, AI.ASSIZ, L., 1862, Com. Nat. Hist. I'. S., vol. 4, pp. 542, \^\. HAM KM , 1X64, Jena. Zeitsrli. fur 



Naturw., Bd. I, pp. 338, 339. -FoRin.s, \X^, Hntisll N,iked-eved Medusa-, pp. 71, 72. 

 Euph\ia, A(.ASSIZ, A., 1865, North Amer. Acal., p. 1*0. UK. MOW. i'jc>4, Bull. Mus. Comp. Zool. at Harvard Coll., vol. VI. 



p. 251. VANHOKFFN, 1891, Zool. An/eiger, lid. 14, p. 443. 

 Ku/>h\sora, MAAS, 1905, Hydromeduscn der Siboga Kipediiion, p. 6. 

 Heterosirf>hanus + Stcenslrupia+ Eaf>h\sa, HARTLALB, 1907, Nordischcs Plankton, Nr. 12, pp. 74, 76, 80. 



