78 AMERICAN HYDROIDS. 



OBELU GRACILIS Calkins. 



Plate 19, figs. 2-4. 



Obelia gracilis Calkins, Some Hydroidg from Piiget Sound, 1899, p. 353. 



Obelia gracilis Hartlaub, Hydroiden aus dem Stillen Ocean, 1901, p. 353. 



Obelia gracilis Mayer, Medusjs of the World, vol. 2, The Hydromedusse, 1910, p. 253. 



Obelia gracilis Eraser, West Coast Hydroida, 1911, p. 39. 



Trofliosome} — Colony erect 11 mm. in height. Stem simple. Main stem flexuose, 

 giving off pedicels at the bends. Pedicels usually in pairs, both individuals of a pair, however, 

 being given off from the same side of the stem, the pairs alternatmg in position. Tlie two 

 pedicels of a pair are of unequal length, one being noticeably shorter than the other; the longer 

 being as much as twice tlie length of the hydrotheca, wliile the shorter is less than half the 

 length of the hydrotheca. Each bears two or more annulations at its base. The hydrothecse 

 are large, campanulate, witli sinuous margin and a well-marked diaplu-agm. Those with the 

 shorter pedicels being noticeably larger than those with the longer pedicels. 



Gonosome. — The gonangia are borne in the axils of the pedicels, one to each pair of the latter. 

 Tliey are much elongated, "club shaped," as Calkins says, with a distinct collar, the blasto- 

 style is covered on all sides by the very numerous medusa buds. According to Calkins the 

 medusffi have 28 marginal tentacles. 



Distribution. — Tlie type and only known locahty is Scow Bay, Port Townsend Harbor, 

 Puget Sound. 



. Bathymetric distribution, 1 to 10 fathoms (?). 



? OBELU PLICATA Hincks. 



Plate 19, figs. 5, 6. 



Obelia plicata Hincks, British Hydroid Zoophytes, 1868, p. 159. 



Obelia plicata Norman, Shetland final Dredging Report, vol. 2, 1869, ]). 256. 



Obelia plicata Maektanner-Turneretscher, Hydroiden des k. k. naturhist. Hofmuseums, 1890, p. 208. 



Obelia plicata Nutting, Hydroids from Alaska and Puget Sound, 1899, p. 741. 



Obelia plicata Calkins, Some Hydroids from Puget Sound, 1899, p. 357. 



Obelia plicata Nutting, Hydroids of Harriman Alaska Exped., 1901, p. 173. 



Obelia plicata Hartlaub, Hydroiden aus dem Stillen Ocean, 1901, p. 351. 



Obelia plicata Mayer, Medusae of the World, vol. 2, 1901, p. 353. 



Obelia plicata Eraser, West Coast Hydroids, 1911, p. 32. 



Laomedia (Obelia) dichotoma (part) Broch, Hydroidenuntersuchungen, No. 3, 1912, p. 54. 



Trophosome.' — Colony considerably broken, but attaimng a height of 16.5 cm. the main stem 

 and the longer branches are fascicled. The component tubes being not so numerous and larger 

 than in Ohelana gelatinosa. The branches become simple in their distal parts and almost white 

 in color. Tlie nonfascicled parts of the branches are annulated just above the origin of the 

 brancUets and pedicels, the annulations being in groups of usually 3 or 4. Tlie pedicels are 

 attenuate, shorter than the hydrothecse and annulated tlnoughout. The hydrothecas are deeply 

 campanulate and much like those of 0. dichotoma. The margin is entire. 



Gonosome. — Gonangia like those of 0. dichotoma (Marktanner-Turneretscher) . 



Distribution. — Tlie type-locaUty is Shetland (J. G. Jeffreys, according to Hincks). Great 

 Cumbray, Scottish coast (Frauenfeld, according to Marktanner-Turneretscher) ; Puget Sound and 

 Orca, Alaska (Nutting); Juneau, Alaska (Kincaid). This species is very close to 0. dichotoma, 

 from which it differs mainly in the fascicled stem. 



Bathymetric distribution, 1 to 10 fathoms?. 



' Description of a specimen from Puget Sound mounted on a slide, kindly loaned the author by Prof. Gary N. 

 Calkins, the discoverer of the species. 



^ The specimen described is from Unalaska, Alaska, where it was collected from piles by Prof. Trevor Kincaid, 

 Sept., 1897. 



