BOUGAINVILLIA MUSCUS. 317 



Colour. — JMain stem greyish green, liydrantlis delicate rose colour. 



Habitat. — " Growing on Fiiscii veslculosus in great abundance." — A. Ar/assiz. 



Bafhi/tiietrical distribiition. — Literal zone.' 



Localities. — Charleston Harbour, M'Crady ; Naushon, Massachusetts, A. Agassiz. 



A medusa obtained abundantly in Charleston Harbour was originally described by M'Crady 

 under the name of Ilippocreiie Carolinensis, and referred by him to a Eudendrinm-Yihi tropho- 

 some from, the same locality, but which he does not describe with sufficient detail for a satisfac- 

 tory diagnosis. 



The same medusa was subsequently traced by Alexander Agassiz to a trophosome of which 

 lie has given the description just cpioted in the diagnosis of the species. 



In the large size attained by the trophosome, Bougainvillia Carolinciisis far surpasses every 

 other species of Bougainvillia as yet discovered. It is, indeed, in this respect equalled by very 

 few hydroids. 



The position of the gonophores on the main stem, as well as ou the branches, brings to 

 mind, as ]\lr. A. Agassiz remarks, the condition of the same parts in the Perigonimus muscoides 

 of Sars. 



5. Bougainvillia muscus, Allman. 



Plate X, iigs. 1—3. 



Perigonimus muscus, — Allman, in Ann. Nat. Hist, for January, 1803. 



Bougainvillia muscus, — Allman, in Ann. Nat. Hist, for May, ISGi. Hi7ic](s, Brit. Hydr. 



Zoopb., p. 111. 



TROPHOSOME. — Hydrocaulus consisting of numerous erect non-fascicled 

 stems, which spring at intervals from a creeping stolon and attain a height of about 

 half an inch ; main stems sending off short branches, which are themselves for the 

 most part without further ramification ; perisarc slightly corrugated. Htdeanths 

 with about sixteen tentacles, alternately elevated and depressed in extension ; body of 

 hydranth invested with a thin continuation of the perisarc, which extends nearly to 

 the base of the tentacles. 



GONOSOME. — Gonophores borne on rather long peduncles, which spring singly 

 or rarely in greater number from the hydrocaulus, at a short distance below the 

 hydranths. 



Colour. — Hydrocaulus light brown, hydranths light reddish brown, manubrium and marginal 

 bulbs of medusa vermilion. 



' Such, at least, I assume to be the area of its distribution in depth ; the Fitcus vesictitosus, on 

 which it has been found by Mr. A. Agassiz, being eminently characteristic of the Literal zone. 



