rare PlumuJarian Ilydroid. 311 



'Povcnpine^ in t)ie deep water to the south of the Faroe 

 Islands*. Four colonies of this rare and beautiful species 

 occur amongst material collected bj Dr. A. Bowman, of the 

 North Sea International Investigations, during the autumn 

 of 1908, and handed to me for examination through the 

 kindness of Prof. D'Arcy W. Thompson, C.B. They were 

 dredged in the Faroe Channel (Station 19 a, lat. 60° i56' N., 

 long. 4° 46' W.) at a depth of 1030 metres, in the immediate 

 neighbourhood of the places from which the type specimens 

 were obtained. 



The colonies vary in height from 4 to 7"5 cm., and in 

 general agree with Allnian's description, but as regards their 

 minute structure these additions and corrections have to be 

 made. The colonies are fascicled for the greater part of their 

 length, but only the anterior tube is divided into internodes, 

 upon each of which a single hydroclade is borne. Allman's 

 figure (pi. Ixviii. fig. 1 A) errs in indicating that the hydro- 

 clades arise from different components of the fascicle. The 

 hydroclades are alternate and rest on short processes from the 

 stem. The hydrothecse are deep and cylindrical, with a 

 straight profile, an aperture lying at right angles to the long 

 axis of the stem and in line with a hydrocladial node, and 

 a margin bearing an anterior prominent tooth accompanied 

 by a smaller tooth on each side. About five indefinite 

 sinuations also occur on each lateral margin. 



Within the hydrocladial internode are several well-defined 

 ridges, five generally springing from behind the hydrotheca, 

 and a number, varying from two to four, from its base. One 

 or two shorter ridges project into the proximal portion of the 

 internode from its anterior wall. A prominent septum, perfo- 

 rated by a minute opening, traverses the mesial nematophore 

 near the point where it becomes free, and from about the same 

 level a strong anterior intrathecal ridge extends horizontally 

 backwards almost to the posterior wall of the hydrotheca. But 

 there is no definite relationship between the position of the 

 intrathecal ridge and that of the nematophore septum, the 

 former being sometimes at exactly the same level as the latter, 

 sometimes above it or below it. The mesial nematophore 

 reaches halfway up the hydrotheca and is free for about half 

 its length, except on the proximal internode of each hydroclade, 



* Allman, J. G., 1874, " Report on the Hydroids collected during the 

 Expeditions of H.M.S. ' Porcupine,' " Trans. Zool. Soc. London, vol. viii. 

 p. 478. 



