ANTHOMEDUS^E ZANCLKA. 



S'.) 



The hydroid stock has heen described by Murbach under the name of "Cor\nitis 

 agiissizii," but is evidently a Gtmnmria. The hydranths are 1.5 to 2 mm. in length and 

 arise singly from a slender, thread- 

 like, anastomosing hydrorhiza. The 

 hydrorhiza is covered with a dc-h- 

 cate perisarc, but this does not 

 extend over any part of the hy 

 dranths. In this respect the species 

 is very different from Z. costiiin. 

 The hydranths are also more cylin- 

 drical and uniform in width through- 

 out the polypite than in Z. fostatn. 

 The tentacles are irregularly ar- 

 ranged and the medusa-buds are 

 found not only near the base of the 

 hydranth, but scattered along the 

 sides. In Zanclea costata they are 

 confined to a zone immediately under 

 the lowest circlet of tentacles. The 

 color of both forms is quite similar, 

 excepting that the hydrorhiza is deep 

 pink in the Z. gemmosa and rosin- 

 yellow intheZ.co.sta/rt. W.S.Wallace 

 found this hydroid growing upon 

 floating Sargassum at Tortugas, 

 Florida, in July, 1908. 



The young medusa 

 here figured was obtained 



at Newport, Rhode Is- Fic.42. Z0nr/fagfmmo5a,fromFewkes,inBull.Mus.,Comp.Zool. at Harvard College. 



land, and was identified by Dr. Alexander Agassiz as the young of '/.anclca gemmosa. 

 Z. gemmosa readily devours the medusae of Obeha. 



Zanclea iraplexa Allman. 



Cor\nt pelAgiea+ Corytif implexa (hydroid and medusa), ALDER, 1857, Catalogue Zoophytes Northumberland, Trans. Tync- 



sidc Nat. Field Club, vol. 3, pp. 13, 18 (of the "separate"), plate 7, figs. 1-6. 

 Zanclea implexa, ALLMAN, 1864, Annals and Mag. Nat. Hist., vol. 13, p. 357. HINCKS, 1868, Hist. British H^lr.n.l /.. ',,).. 



p. 59, plate 9, fig. 3. HARTLAUR, 1907, Nordisches Plankton, Nr. 12, p. 116, fign. 106-111 (list of localities, authors, 



and best description of the medusa). 

 Gemmariii implexa, ALLMAN, 1871-72, Monog. Tubularian Hydroids, pp. 223, 290, plate 7, figs. i-io. H \M x n . iX-<>. V. i. 



dcr Medusen. p. 105. JICKELI, 1883, Morphol. Jahrbuch, Bd. 8, p. 6n, taf. 26 (hi-riiWv ). CKJ, N-. 4 . Arbeit 



Zool. In.st. \Vien, Bd. 5, p. 353. BROWNE, 1896, Proc. Zool. Soc. London, p. 461. HARI.ITT, 1904. Mnth. /.nol. Si.iiinn 



Neapel, Bd. 16, p. 574, taf. 22, figs. 27-29 (hydroid and medusa from the Bay of Naples). BKOWNI, 1905, Proc. Roy. 



Soc. Edinburgh, vol. 25, p. 750. 



This medusa is closely related to /.unclea gemmosa of the Atlantic coast of the I'mted 

 States, but it is much more swollen than the American form, and differs in other n-spivts. 



The bell is globular with fairly thin side walls and a thick, solid, dome-like apex. It 

 is 1.5 mm. high, 1.75 mm. wide. There are 4 prominent nematoryst tracts extending one- 

 fourth to half the distance from the tentacle-bulbs up the sides of the bell, and the nettle- 

 cells in each tract are arranged in two rows. 



There are usually 2 long tentacles 1 80 apart alternating with 2 short tentacle-bulbs, 

 but according to Browne, 1905, the medusa may become mature with 2 or with 4 long ten- 

 tacles. The long tentacles are about twice as long as the bell-diameter and their upper, 

 abaxial sides bear each a double row of numerous filaments, which terminate in oval capsules 

 containing 4 to 8 nematocvsts. The basal bulbs of the tentacles are globular, and lack ocelli. 



There is a slight linear (glandular?) swelling occupying the middle third of each of the 

 4 radial-canals. The stomach is mounted upon a short peduncle and is urn-shaped, with 

 a simple, round mouth-opening. The gonads surround the stomach and are more or less 



