316 BOUGAINVILLIA CAROLINENSIS. 



a mere conical papilla ;" pcrisarc continued as a thin film over the posterior part of 

 the hydranth. 



GONOSOME. — GoxopnoRES scattered irregularly on the ultimate ramuli. ]\Iature 

 MEDUSA Avith a broad and round manubrium, and with the abial tentacles profusely 

 branched. 



Habitat. — Attached to rocks, shells, and occasionally to seaweeds. 

 Locality. — Atlantic coast of North America. 



The Boin/ainvillia siqjerciliari.s was first described by Agassiz, but only from the medusa, 

 with which alone he was at the time acquainted, and whose structure he has made the subject of 

 a laborious and exhaustive treatise.^ He afterwards discovered the trophosome, which he figures 

 in his ' Contributions to the Nat. Hist, of the United States,' while an effective woodcut of the 

 adult medusa, as well as of the entire hydroid, is given by Alexander Agassiz in his ' Illustrated 

 Catalogue of North American Acalephae,' where he has traced the medusa from the period of 

 its detachment from the trophosome to its fully developed state. 



The mature medusa appears to belong to the form with a wide and rounded manubrium 

 and with profusely branched labial tentacles, to which Agassiz would restrict the name of 

 Boiigaitivillia, assigning to those with a more cylindrical manubrium and more sparingly 

 branched labial tentacles Steenstrup's name of Maryelis. I cannot, however, as already said, 

 accept the generic value of this difference. (See above, p. 311.) 



I have never met with Boi'f/ainvillia siiperciliaris. It has not been discovered on the 

 European side of the Atlantic, and the diagnosis here given has been framed from Agassiz's 

 description. 



*^* 4. BorGAiNviLiiA Caeolixensis, M'Crachj. 



HiPPOCRENE Carolinexsis, — M'Crachj, Gyranopb. Charleston Harbour, p. 164, pi. x, figs. 



8—10. 

 Margelis Carolinensis, — A(jassiz, Contr. Nat. Hist. U.S., vol. iv, p. SW. Alex. Agassiz, 



Illustr. Catal, N.A. Acalepbre, p. 156, figs. 241—248. 



TROPHOSOME. — Htdrocaulus attaining a height of from eight to twelve 

 inches ; " the main stem is stout, and tapers gradually ; the main branches begin 

 close to the root, and thus form clusters, from which branch off irregularly secondary 

 branches, which are quite slender and ramify but little." — Alexander Agassiz. 



GONOSOME. — GoxoPHOREs "making their appearance all over the stem." — 

 A. Agassi:. Mature medusa with narrow manubrium, and with labial tentacles about 

 three times bifurcated. 



' ' Contributious to the Natural History of the Acalephae of North America.' 



