110 MESSES. E. W. L. HOLT AND W. M. TATTERSALL— BISCATAX PLANKTON: 



track of nets hauled through the same strata by day, unless it repaired to lower strata, 

 Avhich does not appear to have been the case, since many day-nettings between 400 and 

 100 fathoms give no account of it. "We suppose that the table demonstrates that the 

 species is subject to no marked diurnal vertical movement, but is, imder such conditions 

 of locality, season, and weather as obtained during the period of observation, an 

 inliabitant of the upper hundred fathoms. It would further appear that specimens of 

 19 to 35 mm. are sufficiently sharp-sighted and active to avoid nets fished in the 

 daytime, even as deep as 100 fathoms *. 



Nematoscelis megalops is the only other species of which the hourly occurrence seems 

 to be worth reproducing in tabular form. In activity, apart from considerations of 

 size, we judge it to be intermediate between Stylocheiron and Eujilmusia. Its visual 

 apparatvxs is practically the same as that of the former, but whether such an apparatus 

 is, for the purpose of escape from nets, more or less effectual than the homogeneous eye 

 of Ewplumsia and Ileganyctrphanes is purely a matter of conjectu.re. To us the table 

 suggests that Nematoscelis is subject to diurnal vertical movement, but we cannot deny 

 that the comparative immunity of the species from capture at or near the surface in 

 daylight may have been due to its perception of the approach of nets. 



In this connection it may be permissible to advert to a familiar organism, the pelagic 

 larva of the lobster {Romariis). Observed in an aquarium, or at the surface from the 

 ship's side, it appears to be a feeble and helpless creature. Tet, though obviously a 

 most abundant item in the coastal plankton, it is, as far as our observations go, rare in 

 tow-nets, and seems to afford an illustration of the ease with which even a slowly- 

 swimming crustacean can avoid capture. 



In regard to Eucopia unguicidata, of which ten specimens were taken. Dr. Fowler's 

 nets give the first indication of the vertical distribution. It was certainly taken by the 

 ' Research ' at least as deep as 750 fath., and at least as near the surface as 200 fath., 

 and this is all that can be afiirmed from any source of information. 



With the specific determination of the material entrusted to us, and with the 

 discussion of the vertical distribution of species by night and day, our task appears to 

 be fulfilled. Considerations of temperature, &c., will no doubt be discussed by 

 Dr. Eowler in the final summary of results, -when all organisms detected can be treated 

 together. 



Taken by themselves, the Schizopod gatherings appear to give no very important 

 results in regard to the influence of temperature on distribution. Stylocheiron Sulmiii 

 and S. abhreviatimi, which are not known as Boreal forms, occur only in the strata which 

 reach 52° P. (11° C.) or more ; but Meganyctip)hanes, which is a Boreal and Arctic form, 

 and must endure much lower temperatures in the nortliward part of its range, was 

 apparently confined to the same strata. Nematoscelis megalops, also a Boreal form, was 



* We ^^'rite only of the ' Eesearch " results. The species certaioly occurs at the surface, or quite near it, at 

 night off the west of Ireland, and has been cast ashore in quantity on the North coast. In the Irish Sea, which is 

 shallow, it is common at inconsiderable depths. Though it is taken far to sea in the upper strata of very deep 

 water, we do not regard it as a truly oceanic form (</. H. & T., op. cit.). 



