146 Eev. T. Hincks on Deep-water 



XXII. — On Deep-water Hydroida from Iceland. 

 Bj the Rev. Thomas Hincks, B.A., F.R.S. 



[Plates VI., VII., & VIII.l 



Some years have ela])sed since Mr. Busk placed in my hands 

 a bottle containing some northern Hydroida and Polyzoa 

 which had been obtained by Dr. Wallich. The contents have 

 been long since partially examined, and some of the results 

 have been already published ; but no separate report upon them 

 has appeared, and some new forms which they have yielded 

 are still undescribed. I propose therefore in the present 

 paper to deal with the Hydroid portion. The gathering, 

 though a very small one, is characteristic and interesting. It 

 was taken up from a depth of 100 fathoms off E-eikiavig, 

 Iceland, " amongst icebergs, grounded and drifting." The 

 number of species observed is only seventeen ; and of these a 

 large proportion belong to the Campanularian group of the 

 Lafoeidas. The extreme north seems to be in a special manner 

 the home of the minute forms composing this family. No less 

 than twelve species have been obtained off the coast of Norway 

 by Dr. M. Sars and his son G. Ossian Sars, whose name is 

 so honourably connected with the early history of 'deep-sea 

 dredging. To these must be added four more, which I have 

 found amongst the Icelandic dredgings, raising the whole 

 number of Lafoeids. known to inhabit the northern seas to 

 sixteen. The British species number eleven. 



These Hydroids are mostly inhabitants of deep water ; off 

 the coasts of Norway many of them occur at depths of from 

 50 to 100 fathoms, others at depths of 150, 200, and 300 

 fathoms respectively. The Icelandic specimens, as I have 

 mentioned, were taken up in 100 fathoms *. A few of the Nor- 

 wegian species occur in shallower water, ranging from 20 to 

 50 fathoms ; but they constitute a very small proportion of the 

 whole number. Some have a wide bathymetrical range : thus 

 Lafoea dumosa occurs in the littoral or Laminarian region, 

 and has been dredged in 145 fathoms ; and L. gracillima, 

 which I have obtained in great luxuriance at Oban in 15—20 

 fathoms, has occurred to G. O. Sars off the island of Hvitingso 

 in 150. FiJellum serpens^ the common parasite of some of the 

 larger Sertularians in the " Coralline zone," ranges, according 



* During tlie ' Porcupine ' expedition a Lafoea was dredged up from a 

 depth of 345 fathoms. It was obtained ft-om the " cold area " between 

 Shetland and the Faroe Islands, at a point where the temperature of the 

 water varied from SO'^'-S Fahr. to 29°-8 Fahr, {vide Allman's ' Tubularian 

 Hj'droids,' part ii. p. 165). 



