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Show 1893.] PLANKTON OF THE PAEROE CHANNEL. 993 From S. blpunctata it is readily distinguished by the number of teeth in the accessory rows aud the proportions of tail to body. A row of stout processes is placed on the ventral side of the rows of accessory teeth. These appear to correspond to tbe " follicoli vestibolari " of Grassi; but in forming a single row they differ from those which he figures as characterizing S. hexaptera 1. I have been unable to detect any trace of a " corona cigliata " (Riechorgan) on the dorsal surface of the head and neck. This species2 appears to be present in both the " cold " and the " warm " areas a of the Faeroe Channel, and to be a characteristic component of the " Mesoplankton," 1. e. the floating and swimming organisms between a depth of +100 fathoms below the surface and a depth of + 1 0 0 fathoms from the bottom. Horizontal distribution : 61° 18' N., 4° 21' W., to 59° 42' N., 7° 7' W. Vertical distribution :- Greatest depth-warm area-Sta. 19 a, 480 to 350 fathoms; temp. 46° to 47° F. Greatest depth- cold area-Sta. 13 g, 465 to 335 fathoms ; temp. 31° to 33° F. Least depth-Sta. 13 I, 100 to 0 fathoms ; temp. 48° to 54° F. The least depth given above was the only occasion on which it was taken anywhere near the surface, except for one doubtful and broken specimen at the surface at midnight (Sta. 15). There is no doubt that this species is essentially Mesoplanktonic, with a very wide temperature range (at least 33° to 48° F.); it occurred in every haul, but one, of those made between 530 and 100 fathoms (I. e. in eight out of nine hauls) ; it occurred in every haul which began at or lower than 300 fathoms and finished at the surface (three hauls); <and was taken, certainly, only once in a haul which began at 100 fathoms and ended at the surface (once out of twenty-two hauls). SPADELLA (KBOHNIA) HAMATA, Mobius. (Plate L. fig. 4.) Having obtained a large number of well-preserved specimens of this species, I think it worth while to give an outline (fig. 4) of the external form, since both the original figure of Mobius4 (which has been simply copied by Hertwig 5 and by Grassi6) and also the 1 Grassi, loc. cit. infra, pl. iii. fig. 6. 2 I a m anxious to leave tbe discussion of tbe bathyroetric limits of the species taken on H.M.S. ' Research,' and of the means used to determine these limite, till tbe material has been more fully investigated. At the same time, in describing a new species it is necessary to provisionally indicate the depth &t which it was taken ; but remarks under this heading must be for the present considered as provisional, except in the case of surface forms. 3 For an explanation of these areas, see Wyville Thomson, ' Depths of tbe Sea.' London, 1874. 8vo. .. 4 Jahresb. Commiss. wissenschaft. Untersuch. deutschen Meere, Jahrg. n., iii. p. 158, pl. iii. fig. 13. . , . . . . . »» 5 " Die Ohaetognathen," Jenaische Zeitschnft, xiv. pl. ix. fig. 7. 6 " I Chetognati," Fauna und Flora Golf. Neapel. v. pl. i. fig. 5.^ |
