.„ HYDROIDA II 



40 



hydrothecffi are low, often hardly more than an opening in the apopliyse, which is distally placed, and 

 distinctly marked. The secondary hydrothecee are likewise small, with a fairly large basal chamber, 

 which is almost always symmetrically developed. The hydrothecaa have a thin, bnt well-developed 

 diaphragm; they expand towards the aperture, but have no outward curving margin. 



The gonothecte are small, and attached to the apophyse at the base of the primary- hydrothecje 

 The males are cylindrical to elongated oval, tapering downwards, broadly rounded distally, or cut off 

 transversely. The female gonothecse have a laterally placed opening with a pair of hydranths; the 

 opening margin has on its inner (adthecal) side a short, broadly lingueform protuberance. The gono- 

 theca openings are situated between the middle and the distal end of the gonotheca, rarely quite 

 distally. The gonotheca is often somewhat irregularly bent. 



Material : 



"Ingolf St. 31, 66°35' N., 55°54' W., depth 88 fathoms 1,6° 



- - 34, 65°i7' N., 54°i7' W., - 55 - 



Greenland: Sukkertoppen (without further details) 



Davis Strait, depth 100 fathoms (without further details) [labelled Haleciiim Bcanii\ 

 Iceland: Vadlavik, (depth not stated) [labelled Halecium Bcam'i] 



Between Iceland and The Faroe Islands: 63°i5' N., 9°35' W., depth 270 fathoms [labelled Hale- 

 cium Beanii\ 

 The Faroe Islands: Deep hole at north point of Nolso, depth 100 fathoms 



6i°4o' N., 7°4o' W., depth 135 fathoms 

 Kara Sea: "Dijmphna" [labelled Halecium Beanti]. 



It is not without a certain doubt that we can admit Haleciiim scuhiiii as a distinct species 

 and not as an arctic form of Halecium. kalecimo)/. From a geographical point of view, as also with 

 regard to most of the variational features, it stands in almost exactly the same relation to the last- 

 named species as the arctic forms of several other more or less cosmopolitan hydroids. And it is also 

 Halecium. scutum which has formerly (Broch 1909 p. 144) been noted as forma gigantea of Halecium 

 halecinum. 



A comparison of the two species reveals various points of resemblance. Bonnevie's state- 

 ment (1899 p. 57) "ramification in all planes" as a characteristic feature cannot be admitted; it applies 

 as a matter of fact far more to the exceptions, the great majorit\- of the colonies exhibiting a decided 

 main plane in which the ramification takes place. On the other hand, the short and broad internodia 

 (fig. XIV «) are typical, and differ not a little from Hahcium Bcaiiii, with which the species has espe- 

 cially been confused. The secondary hydrothecse differ normally from Halecium halecinum in having 

 a symmetrical and proportionately lower basal cavity, and from Halecium Beavii in having the plane 

 of the aperture perpendicular to the longitudinal axis. — The frequent confusion of Haleciniii scutum 

 with Halecium Beanii is due to the great variability of the female gonotheca; (figs. XIV l>—h) which 

 not infrequently (f— /) resemble strongly those of the latter species. We should, however, note that 

 in Halecium scutum the aperture and its short neck are as a rule obliquely ]3laced, diverging widely 

 from the line between the stalk of the gonotheca and its top; in addition, the gonotheca has an 



