Hydroida from Deep Water. 133 



A reference to M. Sars's more detailed description of his 

 L.fruticosaj in his paper " Bemajrkninger over fire Norske 

 Hydroider" (1862), will show that it is very different from 

 the form which his son has now figm-ed. The latter has a 

 regular, campanulate calycle of considerable breadth ; the 

 calycle of the former is described as bearing a general resem- 

 blance to that of L. dumostty and as being slightly bent, with 

 the convex side of the curve turned upwards, or occasionally 

 reversed. In short, it is represented as being tuhidar and hent^ 

 whereas the hydrotheca in G. O. Sars's figure is campanulate 

 and straight. The only differences which Prof. Sars could detect 

 between his species and Alder's were that in the latter the ca- 

 lycle was rather more slender than in the northern form, and the 

 pedicle " loosely twisted " instead of being distinctly ringed. 

 But Alder's L. gracilUma has a long, nan-ow, tubular calycle, 

 totally unlike that which the younger Sars has figm-ed in his 

 paper. I have, however, other and very conclusive evidence 

 that the L. fruticosa is not what the last-named naturalist 

 supposes it to be. Prof. Sars and Mr. Alder corresponded 

 about their species and exchanged specimens ; and I have in 

 my possession a bottle sent me by the latter, and labelled by 

 him, containing Norwegian examples of L. fruticosa^ ichich 

 he had received from its discoverer. From these specimens 

 the figures (Plate VI. figs. 8-10) accompanying my paper on 

 Icelandic Hydroids in the present number were drawn (with the 

 camera lucida) ; beside them I have placed a pair of calycles 

 (Plate VI. figs. 6, 7) from specimens of L. gracilUma di-edged 

 at Oban. The close similarity between the two is at once 

 apparent; the ^rm may be said to be identical in both ; and 

 the only difference between them to which I should be dis- 

 posed to attach the slightest significance is found in the cha- 

 racter of the pedicle. In the British form it is merely twisted 

 into two or three imperfect whorls ; in the northern it is com- 

 posed of three or four rings. Sometimes they are almost 

 obsolete (Plate VI. figs. 9, 10) ; but traces of them may always 

 be detected. I confess I cannot regard this trifling variation 

 as a specific distinction, and must therefore continue to rank 

 the L. gracilUma of Alder as a synonym of the older L. fru- 

 ticosa of Sars. 



I may add that, in his account of the latter species, Prof. 

 Sars has remarked on the thinness and delicacy of the mate- 

 rial composing the calycles, and tells us that when dried they 

 collapse and shrivel up. The same holds good of L. gracil- 

 Uma ; but in the case of Lafoea grandis (to which I refer 

 G. U. Sars's figures) the walls of the hydrotheca^ are of very 

 stout material, and retain their form in dried specimens. 



