HYDROIDA II 



1-5 



Greenland: Egedesminde, depth 30—40 fathoms 



Sukkertoppen, on Boltenia (no details noted) 



Ingmikertok, Angmagsalikfjord (depth not given) (East-Greenland Expedition) 

 Iceland: 33 miles SE. t l 2 E. of Stokkesnses near Hornsvig, depth 84 fathoms (labelled Lafoea 

 fruticosa). 



We have here a species of highly variable character, especially in the northern waters, where 

 the biophysical factors evidently exercise an important and determinative influence upon the variation 

 of the species. There is consequently also much confusion as to the synonymy of the species. Lafoea 

 fruticosa was established by M. Sars (1849) an( ^ m ^ s description we find the following with regard 

 to the hydrothecse: "superne latioribus, inferne coarctatis". This certainly gives the impression of a 

 hydrotheca having its lower portion, partly on account of the curvature of the wall, broader than the 

 upper, which again expands nearer the opening. The same is also seen in the drawing subsequently 

 given by G. O. Sars (1873 Tab. IV, figs. 17 — 18) of the species, undoubtedly based upon M. Sars's 

 type specimens. This does not agree with the statements of Bonnevie (1899 p. 65) and we can 

 hardly help feeling that among Bonnevie's Lafoea fruticosa there must also be some colonies of 

 Lafoea gracillima forma eleganfula\ a supposition which is, moreover, confirmed by the study of her 

 material in Christiania. On the other hand, Bonnevie has (I.e.) established an entirely new species, 

 Lafoea symmetrica, which as a matter of fact is based upon variants of Lafoea fruticosa. The principal 

 difference between Lafoea fruticosa and Lafoea symmetrica is, according to Bonnevie, the fact that 

 the latter species has symmetrical hydrotheca;, whereas these are of asymmetrical structure in the 

 former. It will be seen, however, from the drawings of hydrotheca; given (1899 Tab. V, fig. 2 c') that 

 asymmetrical hydrothecte can also occur in Lafoea symmetrica. On the other hand, further examina- 

 tion of the hydrothecae in Lafoea fruticosa (cf. Broch 1908 fig. 4, 1909 textfig. 19) shows that the asymmetry 

 is often but very slightly pronounced, and even disappears altogether in a greater or lesser percen- 

 tage of the hydrothecse in a fairly large colony. We find, in other words, that in this respect, every 

 imaginable transition form may be met with from Lafoea fruticosa to JLafoiia symmetrica; the character 

 in question is therefore not suitable for purposes of specific distinction. There remains then, the size, 

 which is said to differ as between Lafoea fruticosa, L. symmetrica, and L. grandis. It is soon found, 

 however, that this character likewise is here unserviceable. On the one hand, the three species form, 

 according to Bonnevie, a finite series of sizes, Lafoea symmetrica being from the drawings and de- 

 scription, larger than Lafoea fruticosa, but smaller than Lafoea grandis. On the other hand, a large 

 material of the three forms reveals the fact there is no discernible interval throughout the series; all 

 intermediate stages are found, from finely built colonies of Lafoea fruticosa to such extreme cold-water 

 variants as those upon which Hincks's L^afoia grandis is based. We are thus compelled to include 

 the forms under one species, the correct name of which should be Lafoea fruticosa. 



The amalgamation of these three species into one. however, involves the further abolition of 

 Lafoea poc ilium Hincks (1868 p. 204, pi. XL, fig. 2). The shape of the hydrotheca; is very correctly 

 described by Hincks as follows: "tumid below, with the sides curved inwards above, and expanding 

 again slightly towards the top". This coincides entirely with M. Sars's "superne latioribus, inferne 

 coarctatis". The length of the stalk in Lafoea species and its spiral winding or division into separate 



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