vol. i.i Torre y. — Hydroida of the Pacific Coast. 29 



This is in all probability the hydroid that A. Agassiz ('65, 

 p. 152) suggests may be the hydrarrum of Bougainvillia (Hip- 

 pocrenej mertensii. There is nothing in his notice to indicate 

 that he saw the gonosome on the hydroid, and that would account 

 for a mistake in referring a free medusa to a form with fixed 

 sporosacs. His brief description, so far as it goes, answers well 

 for the present species. So far as I know, there is no Bougain- 

 villia in San Francisco Bay. 



Bimeria robusta, sp. no v. 



PI. I. Figs. 5, 6, 7. 



Trophosome. Hydrorhiza encrusting. Stems and larger branches stout, 

 polysipkonic. Colony may be 13 cm. long, longest branches 4 cm. or even 

 (i cm. long. The latter arise irregularly. Hydranth pedicels from these, or 

 from secondaries which are always short (6-8 mm.) and may bear 2-4 

 hydranths. All branches rather closely associated. Perisarc wrinkled 

 throughout, investing the hydranth body and possibly bases of the tentacles. 



Hydranths fusiform, with conical proboscis, the largest with 11 tentacles, 

 rarely 12, in one ease 16. Five tentacles are longer and often stouter than 

 the others, subequal, suberect, and belong to the first whorl. The tentacles 

 of the second whorl, alternate with these, are shorter, subequal, and bend 

 downward. 



Gonosome. Absent. 



Distribution. San Pedro, Cal. Covered with diatoms and 

 Tentaculifera. Growing in company with Endendrium rameum 

 and Tubularia crocea, on the float at the ferry landing. 



This species is placed provisionally in the genus Bimeria 

 until the character of the gonosome shall have been determined. 



Perigonimus Sars. 



Trophosome. Hydrocaulus branched or simple, rooted by a filiform 

 hydrorhiza. Hydranth fusiform with conical hypostome. 



Gonosome. Free medusa 1 , with either two or four marginal tentacles 

 with bulbous bases but without ocelli. 



Perigonimus repens (Wright), Hincks. 



Atraetijlis repens, Wright, Proc. Roy. Phys. Soc. Ed., I, p. 450. 

 Perigonimus repens, Hincks, Brit. Hyd. Zooph., 1868, p. 90. 

 Perigonimus repens, Calkins, Proc. Bot. Soc. N. H., 1899, XXVIII, No. 

 3, p. 339. 



Distribution. Sausalito, Cal., between tides. Townsend Har- 

 bor, Wash. (Calkins). Great Britain (Allman). 



