452 ON THE FAUNA AND BOTTOM-DEPOSITS NEAR THE 30-FM. LINE 



Dq)th. To 150 fathoms. 



Habitat. On shells, etc., and very often parasitic on other zoophytes, from moderate 

 dejiths to deep water (Hincks, No. 46). The Pomvicrania took it on a bottom of sand, 

 and on sand, shell, and small stones (Schuke, No. 105). 



Hahxium lahrosum was identified by Mr. E. T. Browne, in Iiauls 73 

 and 75, on Grounds XIV. and VII., west and south-west of the 

 Eddystone. 



DiSTiUBUTlON. Geograiyliical. North Sea, Scotland, Shetlands (fide Hartlaub, No. 

 38). Very common at Heligoland, especially on rhallusia (Ascidiella) virginea. Allman 

 (No. 2) states that this is a northern form, confined to the north coasts of the British 

 Isles. Mediterranean (Carus, No. 14). 



Halecium teneUum was recognised only in haul 29 on the Prawle 



Stony Ground, growing on the stem of Tuhularin indivisa. In haul 



77 on Ground IV. a fragment of a small Halecium, which was probably 



this species, was seen growing on Gellaria. 



Distribution, etc. Salcombe Bay, Devon, on Salicornaria farciminoides ( = Ccllaria 

 fistulosa); Filey (T. H.) ; Northumberland, on Tubularia indivisa and Sertularia abietiim, 

 from deep water (J. A. ) [Hincks, No. 46J. 



Sertularella Gayi (Chart II.). In contradistinction to Halecium 

 halecinum this species is specially abundant on the tine sand grounds, 

 where it forms one of the most characteristic features of the fauna. 

 It is most abundant on the line sand grounds 111. and IV. to the 

 eastward of the Eddystone, and on Grounds VI. and VII. to the south. 

 It is present in quantity also on the fine sand of the inner and outer 

 trawling ground (I. and II.). On the coarser grounds to the westward 

 of the Eddystone, it is still moderately plentiful on the coarse gravel 

 mixed with fine sand of Grounds XL and XII. It is scarce on the 

 remaining grounds in the neighbourhood of the Eddystone (one or two 

 colonies at most in a haul and absent in many hauls), and has never 

 been taken on the Bolt Head Shell Gravel (XVII.) or the Prawle 

 Stony Ground (XVIII.). 



On the grounds upon which it is abundant Sertularella Gayi is most 

 frequently attached to the membranous tubes of Thclepus. It is also 

 found less frequently attached to shells. 



A group of animals of the following kind, in which S. Gayi plays an 

 important part, is exceedingly frequent on the grounds where this 

 hydroid is abundant : — The tube of the polychaete Tlicleinis serves 

 as a base from which the hydroid Sertularella Gayi springs. Attached 

 to the lower portion of the stem of the hydroid are the Ascidian 

 Ascidiella scabra and the Polychaete Sahclla (pavonina ?), as well as the 

 barnacle Scalpellum vulgnre. Attached also to the stem of the Sertu- 

 larella will probably be some of the smaller creeping hydroids, especially 

 Clytia Johnstoni, together with a number of foraminifera belonging to 

 the species Truncatulina lohaiula. 



