HYDROIDA 11 



Some writers unite this species with the two following; this is, however, as I have previously 

 shown (1908 p. 33) not correct. Both in its creeping form and in the upright colonies it is very typi- 

 cally distinct from the remaining northern La/oea species, partly b\- its very slightly asymmetrical 

 hydrothecae, which have practically no real stalk at all, partly by the fact that the hydrothecje, which 

 are set very far apart, form almost a right angle with their corresponding stolon. 



The species is widely distributed in the northern seas (Fig. I). It is a distinctly boreal species, 

 which can, however, penetrate far into southern waters, and has been recorded, for instance, from the 

 Mediterranean (Babic 1910 p. 213). On the other hand, purely arctic conditions seem quickly to set 

 a limit to its progress. 



Lafoea gracillima (Alder) Hi neks. 

 1856 CcDitpaunlaria gracillima, Alder, A notice of some new genera and .species, p. 361, pi. 14 figs. 5 — 6. 

 1874 Lafoea gracillima^ Hincks, Notes on Norwegian Hydroids from deep-water, p. 132. 

 1868 Lafoea pygvicra pars, Hincks, A History of the British Hydroid Zoophytes, p. 205, pi. 40 fig. 3. 

 1887 Lafoea f rut icosa pars, Bergh, Goplepolyper (Hydroider) fra Karahavet, p. 334. 



The colony is creeping or upright, with irregularly branched rhizocaulome formation. The 

 hydrothecse are narrow, tubular, curved, with the convex side turned upwards; the oj^ening margin is 

 on the concave (lower) side never curved outwards, but may be slightly so on the convex side of the 

 hydrotheca. The hydrotheca passes gradually over into the stalk, which is of varying length, and 

 with a spiral coil closer in some, more open in others. In upright colonies, the stalk axis forms as 

 a rule a very acute angle with that of the mother tube, the basal part of the hydrotheca is often 

 nearly parallel with the latter. 



The gonothecre are compressed in hermaphroditic coppinia;, the long tubes of which are as a 

 rule highly curved. The male gonothecge occur wedged in between the female. 



Forma typica: finely built colonies, with hydrothecse set wide apart; the hydrothecse entirely 

 tube-shaped, with loosely spiral stalk, as a rule with two turns. 



Forma elegaiitula: colonies of coarser build, with closely set hydrothecse; the hydrothecae often 

 with the upper part of the opening margin curved slightly outwards; stalk with a varying number of 

 mostly close spiral windings. 



Material: 



Forma typica: 



"Ingolf" St. I, 62°3o' N., 8°2i' W., depth 132 fathoms 7,2° 



- - 55- 63°33' N., i5°o2' W., - 



- - 85, 63°2i' N., 25°2i' W., - 



- - 87, 65°o2,3' N., 23°56,2' W., - 



- 95, 65°i4' N., 3o°39' W., - 



- 127, 66°33' N., 20°05' W., - 

 Iceland: Skagestrand 



9 miles N.74E. of Hornet, east coast of Iceland, depth 38 fathoms 

 62°i7' N., 4°57' W., depth 144 fathoms. 



The Ingolf-Expedition. V. 7. 



