HYDROIDA II 



167 



Laomedea geniculata is a cosmopolite, belonging to the upper part of the littoral region ; in 

 northern seas it is chiefly restricted to the Laminaria, but may also occur on deeper-growing Zostera 

 and on shallow red algse in large quantities. Albeit properly cosmopolitan, the species is nevertheless 

 very rare in strictly arctic waters, but may occur here right into the White Sea. It is most frequent 

 in the boreal areas. Along the coasts of Norway, round the British Isles, the Faroe Islands and Ice- 

 land it is present in great numbers (fig. LXXXV). It is also mentioned from Greenland, but no de- 

 finite locality has yet been recorded. 



._ 1000 m. 



Fig. LXXXV. The distribution of Laomedea geniculata in the Northern Atlantic. 

 In the hatched regions the species is abundant. 



Laomedea longissima (Pallas) Alder. 

 1766 Serlularia longissima, Pallas, Eleuchus zoophytorum, p. 119. 



1858 Laomedea , Alder, A Catalogue of the Zoophytes of Northumberland, p. 121. 



1868 Obelia — , Hincks, A History of the British Hydroid Zoophytes, p. 154, pi. 27. 



1868 — flabcllata, Hincks, I.e. p. 157, pi. 29. 



Large graceful colonies with monosiphonic, brown stem, generally flexuous. From this pro- 

 ceed secondarily ramified branches, which again give off a hydrotheca stalk from the apophyse at 

 each bend. There is no thickening of the periderm under the apophyses. The hydrotheca: are about 

 twice as long as broad, slender, inversely conical, with more strongly curved basal part. The hydro- 

 theca margin is more or less curved, at times with distinct teeth, at others quite smooth. The basal 

 chamber is fairly large, and bounded at the top by a finely built but distinct diaphragm. 



