1898.] PLANKTON OF THE FAEROE CHANNEL. 1031 



What appeared to be broken specimens of Aglantlia rosea of 

 Forbes occurred in small numbers in three surface hauls. 

 The eighth species, 



AGLANTHA DIGITALIS (0. F. Miiller, Haeckel pars), 



represents such of HaeckeFs A. digitalis as remains after the 

 restoration of Forbes's A. rosea, and the removal of A. digitalis var. 

 occidentalis Maas J . In his great monograph Haeckel 2 put Forbes's 

 A. rosea with eight marginal vesicles, and the old A. digitalis of O. F. 

 Miiller and Fabricius with four marginal vesicles, under the single 

 species A. digitalis. Since then both species have been confused, 

 until again separated by Browne 3 . It is consequently at present 

 impossible to detail accurately the distribution of these two species, 

 but it seems to be certain that A. digitalis occurs off Greenland and 

 Northern Norway, and that A. rosea occurs as a neritic form round 

 the British coasts (Valentia, Shetland, Heligoland). The one is 

 certainly an Arctic form, the other a southern, even though they 

 may overlap to a greater extent than we at present know. 



This being so, it is not without significance that Mr. Browne, 

 when going over my specimens without knowing the horizons, 

 separated the Aglanthce into two groups, A. rosea and A. digitalis, of 

 which, on comparison with the station list, all the A. rosea were found 

 to come from surface hauls, all the A. digitalis from deep hauls 4 . 

 As A. digitalis was captured in 66 / of Mesoplankton hauls, and 

 never at the surface, the presumption is that it has, like other 

 Arctic surface forms, sunk to deeper strata on reaching lower 

 latitudes (warmer surface water). 



Unfortunately the results of the ' National ' do not throw any 

 further light on the distribution of these two species, horizontally 

 and vertically, for Maas (op. cit. supra) accepted Haeckel's 

 fusion. 



TBACHYNEMA sp. 



A few specimens of a large medusa were apparently referable 

 to this genus. Hemispherical in shape (15 mm. diain., 12 mm. 

 high), its eight radii showed the heavy transverse musculature of 

 Trachymedusce. The eight tentacles were stumpy and thick, one 

 at the end of each radial canal. The sense-organs had disappeared. 

 The manubrium was about 5 mm. long, devoid of a " Magenstiel," 

 and provided with four very small oral lappets. What seemed 

 to be rudiments of generative organs were placed on the upper 

 third of the radial canals. 



1 O. Maas: Ergebnisse d. Plankton-Expedition. Die craspedote Medusen 

 24 



2 E. Haeckel : System der Medusen, i. p. 272. 



3 E. T. Browne : Proc. Zool. Soc. 1897, p. 833. 



4 One small specimen of Aalantha, too much damaged for reference to either 

 species, was taken at 166. In the table it has been placed as a query under 

 A. rosea. 



