HYDROIDA II 



39 



males are very elongated oval, the females elongated oval to sausage-shaped, highly curved, with a 

 short cylindrical neck in the middle or on the basal half of the gonotheca, and on the concave side 

 of the same. Opening margin level; in the opening itself a pair of hydrauths. 



Material: 



"Thor" 63°3o' N., 2o°i4' W., depth 80 metres. 



The Faroe Islands: Boronses 13 miles in N75W., depth 30 fathoms. 



On a previous occassion (1913 p. 13) I stated that Halecium Beanii should be regarded as a 

 variant of Halecium halecinum; further investigations have, however, shown that this is not correct, 

 even though the two species, more particularly 

 in a sterile state, may often enough be difficult 

 to distinguish. Fertile female colonies are not 

 easily confused, the form of the gonotheca; being 

 typically different; in comparison with the follow- 

 ing species it should be noted that the aperture 

 in Halecium Beanii lies roughly in a line with 

 the basal and distal end of the gonotheca, and 

 that the neck axis closely approaches, if not entirely 

 coinciding with, this. line. (Fig. XIII). The bran- 

 ches are, in Halecium Beanii, often slenderer than 

 in Halecmm halecimim and Halecium scutum, and 

 the apophyse is somewhat more marked; in addit- 

 ion, the basal chamber of the secondary hydro- 

 theca is symmetrically developed, and not asym- 

 metrical as in Halecium halecinum; finally also, 

 the oblique position of the hydrotheca aperture as towards the axis serves to distinguish Halecium 

 Beanii from the two related species mentioned. 



The geographical data for Halecium Beanii are extremely unreliable as regards the northern 

 waters; the species is, as I have frequently been able to perceive, often confused with Halecium sat turn 

 in arctic, with Halecium halecinum in boreal areas. In all probability, it is a heat-loving form, which 

 exceptionally penetrates into the northern waters. 



Fig. XIII. Halecium Beanii. 



a. Internode with hydrothecae. b. Gonotheca Q. From the 



Faroe Islands, Boronaes 13 miles in N.75W. (X 60. 



Halecium scutum Clark. 



1876 Halecium scutum, Clark, Report on the Hydroids Alaska and the Aleutian Islands, p. 210, 



pi. 10, figs. 13—14. 



Robust colonies with polysiphonic main stem. The outermost small branches exhibit an almost 

 regular pinnate ramification in the same principal plane as that in which the branching of the colony 

 falls; more rarely, the colonies may be quite irregularly bushy. The minor branches are divided up 

 into iuternodia, the length of which is about twice the distal breadth (apophyse included). The primary 



