82 AMEEICAN HYDEOIDS. 



Campanulana didiotoma A. Agassiz, North Amer. Acalephaa, 1865, p. 89. 



Campanularia dkhotoma Hincks, On New British Hydroida, Ann. Mag. Nat. Hist., ser. 3, vol. 17, 1865, p. 297. 



Laomecka dicholoma Parpitt, Additions to Zooph. of Devonshire, Ann. Mag. Nat. Hist., ser. 3, vol. 18, 186G, p. 11. 



Laonicdea dicholoma Alder, Nat. Hist. Trans, of Northumb. and Durham, vol, 1, 1867, p. 49. 



Laomedea dicholoma van Beneden, Recherches sur la Fauna littorale de Belgique, 1867, p. 154. 



Laomedea dichotomy Heller, Zoophyten und Echinodermen der adriatischen Meeres, 1868, p. 44. 



Ohclia dicholovia Hincks, British Hydroid Zoophytes, 1868, p. 156. 



Laomedea dichotoma Herklots, Natuurlyke Historie van Nederland, 1870, p. 399. 



Laomedea dichotoma Allman, Gymnoblastic Hydroids, 1871, p. 28. 



Obelia dichotoma Allman, Gymnoblastic Hydroids, 1871, p. 127. 



Campanulana dicholoma Metzger, Die wirbellosen Meeresthiere der ostfriesischen Kiiste, 1871, p. 35. 



Obelia dichotoma Verrill, Proc. Amer. Ass. Adv. Sci., 1873, p. 364. 



Ohclia dichotoma Schulze, Nordsee Expedition, 1874, p. 129. 



Obelia dicholoma ^^'inther, Fortegnelse over de i Danmark Hydroider, 1879-80, p. 237. 



Obelia dichotoma Marktanner-Turneretscher, Hydroiden des k. k. naturhist. Hofmuseums, 1890, p. 209. 



Laomedea (Obelia) dichotoma Levinsen, Annulata, Hydroida, etc., 1893, p. 369. 



Campanulana dichotoma Bonnevie, Norwegian North Sea Exped., 1898, p. 26; 



Obelia dichotoma Calkins, Some Hydroids from Puget Sound, 1899, p. 356. 



Obelia dichotoma Hargitt, Amer. Nat., 1901, p. 382. 



Obelia dichotoma Hartlaub, Hydi'oiden aus dem Stillen Ocean, 1901, p. 353. 



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



Obelia dichotoma Torrey, Hydroida of the Pacific coast, 1902, p. 57. 



Obelia dichotomy Billard, Cont. h, I'^tude des Hydroides, 1904, pp. 90, 170. 



Obelia dichotoma Torrey, Hydroids of the San Diego Region, 1904, p. 15. 



Obelia dichotoma Billard, Regeneration de 1 'Obelia dichotoma, 1905, p. 1048. 



Obelia dichotoma Bourne, Frith of Clyde medusse, 1905, p. 769. 



Obelia dichotonw=0. australis Hartlaub, Die Hydroiden der magalhaensischen Region und chilenischen Kiiste, 



1905, p. 580. 

 Obelia dichotoma Blllakd, Travailleur et Talisman, Hydroids, 1907, p. 169. 

 Obelia dichotoma Jaderholm, Northern and Arctic Invert., pt. 4, Hydroiden, 1909, pi. 63. 

 Laomedea dicholoma Broch, Die Hydroiden der arktischen Meere, 1909, p. 229. 

 Obelia dichotoma Mayer, Medusse of the World, vol. 2, Hydromedusse, 1910, p. 246. 

 Laomedea (Obelia) dichotoma (part) Broch, Hydroidenuntersuchungen, No. 3, 19i2, p. 54. 

 Obelia dicholoma Eraser, West Coast Hydroids, 1911, p. 38. 

 Obelia dichotoma Stechow, Hydroiden der Munchener Zoologischen Staatssammlung, 1912, p. 356. 



Trophosome} — Colony consisting of an upright stem 3.5 cm. in height and giving off irregu- 

 lar lateral branches, some of wliich again branch in a dichotomous manner. Stem and branches 

 sometimes straight and sometmics sinuous in outhne and with a group of usually 5 to 8 symmet- 

 rical annulations above the origin of each branch or pedicel. Pedicels alternate, short, con- 

 siderably shorter then the hydrothecse and not appreciably diminishing in size from the proximal 

 to the distal ends. There is often a single pedicel in the axil of each branch. Hydrothecse deeply 

 campanulate with very shghtly curved sides, so that they approach a triangle in outline. Margin 

 without teeth, but sometimes with sHght indications of pie atings,. which sometime produce a 

 series of sinuosities around the margin resembUng very low rounded teeth. The diaphragm is 

 low but evident and the coenosarcal connection between hydranth and pedicel is broad. 



Gonosome."^ — "GonothecBe axillary, slender, smooth, widening from the base upward and 

 terminating above in a raised, somewhat conical aperture." The medusa when hberated are 

 "about 1 nma. wide and usually have 16 (occasionally 24) tentacles. Th§ four gonads are adja- 

 cent to the manubrium or the 4 radial canals, but at the. end of three days they are seen to 

 have migrated outward to the middle of the 4 radial canals."^ 



' Description of specimen collected by the author at Plymouth, England, in 1895. 



^Lacking in the specimen described and in all others in the possession of the writer. The description given above 

 is taken from that of Hincks'a British Hydroid Zoophytes, 1868, p. 156. 

 ^Mayer, Medusas of the World, vol. 2, the Hydromedusa;, 1910, p. 246. 



