LEPTOMEDTJSyE — OBELI A. 



255 



Obelia austro-georgia, Jaderholm, 1904, from Cumberland Bay, South Georgia, Antarctic, 

 resembles O. bifurca Hincks, but has only 12 wide shallow teeth and its hydrothecae are 

 smaller and are fluted. The stems become 15 mm. high. This form may not be Obeha, 

 however, but Campanularia for the gonosome is not known. 



Obelia longissima Hincks. 



Serlularia longissima, Pallas, 1766, Elenchus Zoophytorum, p. 119. 



Laomedea dichoioma, var. fi, Johnston, 1847, History British Zoophytes, Edit. 2, p. 102. 



( .') Campanularia gelalinosa, Van Beneden, 1844, Acad. Roy. Bruielles Mem., tome 17, p. 33, plates I, 2. 



Laomedea longissima, Alder, 1857, Trans. Tynes. Nat. Field Club, vol. 3, p. III. 



Obelia longissima, Hincks, 1868, Hist. British Hydroid Zooph., p. 154, plate 27, 3 figs.— Clarke, 1876, Scientific Results Explora- 

 tion of Alaska, vol. 1, p. 212 (from Unalaska, Alaska). — Nutting, 1901, Bull. U. S. Fish Commission for 1899, pp. 351, 

 379, fig. 41. — Bedot, 1901, Revue Suisse de Zool., tome 9, p. 457; Ibid., 1905, tome 13, p. 95 (citation of literature to 

 1850). — Hartlaub, 1905, Zoolog. Jahrbuchem, Suppl. 6, p. 582, fig. E2. 



( ?) Eucope polyslyla, Gegenbaur, 1856, Zeit. fur wissen. Zool., Bd. 8, p. 242, taf. 8, fig. 18. 



Obelia polyslyla, Haeckel, 1879, Syst. der Medusen, p. 117. 



Main stems usually black or horny-brown, and about 300 mm. long, very flexible, and 

 tapering gradually from base to tip. Main stem nearly straight, but slightly zigzag, the angle 

 being at points of origin of the branches. The branches are light-colored and arise at short 

 intervals from the main stem, standing out nearly at right angles to the stem itself. These 

 branches are longest near the base, but shorter higher up, and arise from the stem alternately, 



on opposite sides, in a palmate 

 manner. The branches them- 

 selves branch in a manner simi- 

 lar to that of the main stem. 

 The main stem and each branch 

 are annulated with 3 to 6 rings 

 above the point of origin ot 

 each branch or ramulation. 



The hydrothecx are cam- 

 panulate, quite large, delicate, 

 and elongate. They are nearly 

 conical, with slightly bulging 

 sides. The rims are delicately 

 notched with very small, blunt, 

 shallow teeth. These hydro- 

 thecae are borne upon quite 

 long pedicels, usually ringed 

 throughout with about 8 to 15 

 rings, and tapering from their 

 point of origin to base of 

 hydrotheca. 



The reproductive calycles 

 arise from relatively short pedi- 

 cels in the axils of the stems. 

 They are ovate to conical, with 

 smooth outer surface and with 

 the terminal aperture at the 

 extremity of a crater-like pro- 

 jection. About 10 to 15 me- 

 dusa-buds are seen developing 

 at one and the sametimeineach 

 calycle. The calycles break off 

 very readily, and on this account 

 are rarely seen in preserved or 

 roughly handled specimens. 

 When set free, the medusa has 



Fig. 134.— Obelia longissima, after Hincks, in British Hydroid Zoophytes. 20 to 24 tentacles. 



