20 HYDROIDS COLLECTED BY THE " HUXLEY " FROM 



Bimcria nutans is generally found in the form of an erect arbor- 

 escent colony, but here it was growing as a creeping form, without 

 branches. The hydrocaulus has become a creeping stolon giving off at 

 intervals single hydranths, which are on fairly long stalks. 



A change in the mode of growth is not uncommon among Hydroids, 

 and is one of the difficulties in connection with the drafting of precise 

 generic characters. Arborescent colonies of Syncorync and Bougain- 

 villia, when so placed in small aquaria that a branch is in contact with 

 the glass, will frequently send out a shoot which, on adhering to the 

 glass, becomes converted into a stolon. The stolon develops single 

 hydranths on long stalks, which seldom branch. The mode of growth 

 of the new colony is distinctly that of a creeping form, whereas the 

 old colony retains its arborescent growth. 



Bimeria vestita, Wright. 



At Station II., 75 fathoms, this species was fairly common on 

 Sertnlaria abietina. 



It can at once be recognised by having the lower half of each 

 tentacle sheathed with a layer of perisarc. When the hydranths are 

 in a contracted condition the sheath is scarcely visible, and then a 

 colony looks like a little Bougainvillia. 



Distribution. Firth of Forth (Wright, Allman) ; Yorkshire, Whitby 

 (Hincks); Devonshire, Torbay and Salcombe (Hincks); Start Bay, 

 20-23 fathoms (E.T.B); Lancashire, Morecambe Bay (Allman); Irish 

 Sea (Thornely) ; Ireland, Lough Swilly (Duerden) ; Heligoland (Hart- 

 laub, 1897) ; Mediterranean, near Banyuls (Motz-Kossowska). 



Bimeria arborea, nova species. Plate I., figs. 1-3. Plate 11. 



At Station XIIL, 412 fathoms, was taken a large tree-like Hydroid, 

 which at first sight looked like an aged colony of Bougainvillia, but 

 since the gonophores were found to be true sporosacs, it showed the 

 generic character of Bimeria. 



Description of the species. Trophosome — hydrocaulus well branched, 

 attaining a height of about 3| inches ; branching irregular, with 

 a tendency towards one plane ; stems and branches fascicled ; 

 hydranths with about twelve tentacles in a single verticil; perisarc 

 continued over the lower part of the hydranths in the form of a cup, 

 into which the hydranth contracts. Gonosome — sporosacs situated on 

 the hydrocaulus. 



The specimens consist of a large colony (Plate 11.) and several 

 small pieces. It is quite probable that they all formed part of one 

 colony, which the trawl had torn off above the root. 



The stem and branches have a central axial tube surrounded by 

 a large number of delicate auxiliary tubes. Apparently all the 



