[173] THE HYDROIDS I9I 



than the hydrothecae and sometimes considerably shorter, without a 

 definite swelling below the hydrothecae. Hydrothecae immense, in 

 one case nearly -^ of an inch in height, long, tubular-urceolate, ex- 

 panded distally, with slightly everted and broadly sinuous margin. 

 The margin is reduplicated in one specimen. Hydranth with about 

 twenty tentacles. 



Gonosome. — Not known. 



Distribution. — Orca, Prince William Sound, Alaska (W. R. Coe, 

 Harriman Exped.). 



This species is closely allied to C. grandis Allman,^ and may be 

 identical with it although it differs from Allman's description in the 

 character of the pedicels which he describes as having distinct node- 

 like enlargements immediately below the hydrothecae. The hydro- 

 thecae are larger than those of any other campanularian known to me. 

 But one small colony was found and it was creeping over another 

 hydroid. 



OBELIA. 



Trophosome. — Colony regularly branching ; stem simple or com- 

 pound. Hydrothecae campanulate, thin, never with greatly thickened 

 walls. 



Gonosome. — Reproduction by means of medusae which are disk- 

 shaped, with four radial canals, more than eight marginal tentacles, 

 eight interradial lithocysts and a short manubrium without mouth ten- 

 tacles. 



OBELIA DICHOTOMA (Linn.). 



Sertularia dichotoma Linn., Systema Naturae, Ed. x, p. 812. 1758. 



Obelia dichotoma Schulze, Nordsee Expedition, Hydroida, p. 129, 1872. — 

 Verrill, Preliminary check-list Marine Invertebrates of Atlantic coast, 

 p. 16, 1879. — Calkins, Some Hydroids from Puget Sound, Proc. Boston 

 Soc. Nat. Hist., Vol. xxviii. No. 13, p. 256, 1899. 



Distribution. — Sitka, Berg Inlet, and Orca, Alaska (Harriman 



Exped.) ; British Coast (Hincks) ; Helgoland (Schulze) ; Puget 



Sound (Calkins). 



OBELIA PLICATA Hincks. 



Obelia plicata HiNCKS, British Hydroid Zoophytes, p. 159, 1868. — Nutting, 

 Hydroida from Alaska and Puget Sound, Proc. U. S. Nat. Mus., Vol. 

 xxi, No. 13, p. 741, 1899. 



Distribution. — Orca, Alaska (Harriman Exped.) ; Puget Sound 

 (Nutting) ; British Coasts (Hincks) . 



' Diagnoses of new Genera and Species of Hydroida ; Linnsean Soc. Jour. 

 Zoology, Vol. XI, p. 259. 



