HYDROIDS OF BEAUFORT, NORTH CAROLINA. 361 



Gonothyrsea gracilis (Sars). 



Laomedea gracilis Sars, Bcretning om en zoologisk Reise i Lofoten og Finmarken, 1851, p. 18. 



GonotliyreEa gracilis AAiman, Ana and Mag N. H., 3d ser., xm, 1864. p. 374. Hincks. Br. Hydroid Zoophytes, 1868, p. 183. 



Trophosomc. — Colony irregularly branched; stem, branches, and pedicels long and slender; 

 branches and pedicels bend abruptly- near the origin and pass upward in the same direction as the main 

 stem; stem with several annulations at the base and above the origin of each branch and pedicel; 

 each pedicel with several annulations at the base and below the hydrotheca; hydrotheca long for 

 its width, cylindrical for the upper half or two thirds and gradually tapering to tlie base; teeth 10 

 to 14, deeply cut and rather sharp. 



Gonosome. — Gonophores borne on the hydrorhiza and on the stem, with distinct, annulated 

 pedicels; gonangia oblong-oval in shape, flaring a little at the rim. Each gonophore bears foiu' 

 or five sporosacs. 



Distribution. — On Pennaria growing on the piles of the railroad bridge near Beaufort and on gulf- 

 woed collected on the seaward side of Bogue Bank. This species bears much resemblance to Clytia 

 edwardsi (Nutting) in its general appearance, particularly in the mode of branching and in the shape 

 of the hydrotheca, but the gonosome is entirely different. 



Genus OBELIA. 



Trophosome. — As in the family. 



Gonosome. — Gonophores producing medusse, which when set free have 4 radial canals, more than 

 8 marginal tentacles and 8 lithocysts borne on the base of tlie tentacles; umbrella disk-shaped. 



Key to the Species of Obelia Found in the Beaufort Region. 



A. Hydrothecae with toothed margin. 



Each tooth is provided with two sharp points O. btcuspidala. 



B. Hydrothecae with entire margin. 



a. Hydrothecae with straight sides O. dichotoma. 



b. Hydrothecae nearly bell-shaped, coming off alternately from a geniculate stem which supplies a 



shoulder for each O. geniculaia. 



c. Hydrotheca? bell-shaped with a tendency to a flaring rim. Stem and pedicels much annulated. 



O. hyalina. 



Obelia bicuspidata Clarke. 



Obelia bicuspidata Clarke. Trans. Conn. Acad. Sc.. vol. in, 1S76. p. 58. 

 Obelia bidenlala Clarke. Trans. Conn. Acad. Sc. vol. ill. i3-6. p. 58. 

 Obelia bicuspidata Nutting. Hydroids of Woods Hole, 1901. p. 351. 

 Obelia bideniata Nutting, Hydroids of Woods Hole. 1901, p. 351. 



Trophosome. — Colony small, not much branched; main stem geniculate, annulated at the base and 

 above each branch or pedicel; hydrothecte on short pedicels, except the terminal one, armulated through- 

 out, standing well out from the stem; long and slender, tubular but tapering slightly to the base; margin 

 t(X)thed, each tooth provided with two sharp points; lines are usually found running from the base of the 

 indentations, lengthwise of the hydrothecae. 



Gonosome. — Gonophores very small, borne in the axils of the hydrothecal pedicels, supported on 

 short, annulated pedicels; gonangia ovate or oval, with the top truncated or, in some cases, slightly 

 inverted at the center; some of them are shorter than the hydrothecae. 



o Hydroids of the Bermudas, 1907, p. 473. 6 Biological Bulletin. 1909. p. 373. 



