1903. ] PLANKTON OF THE FAEROE CHANNEL. 129 
Once it occurred in enormous quantity in St. Andrew’s Bay in 
company with WVyctiphanes norvegica, once at Redear with a 
similar swarm of Huthemisto compressa, the latter being also an 
Arctic type-form'. In both these cases it is probable that the 
creatures had been driven down the North Sea by a strong southerly 
current, in the manner which I have already suggested’ for 
Parathemisto oblivia; and it has therefore no more right to be 
regarded as a “ British” species than an occasional Velella or 
Tanthina brought up by the North Atlantic Drift to our shoves. 
According to Ortmann (op. cit.), the ‘ National’ hauls gave no 
indication of the vertical distribution of this species. 
Tt will appear from the table (p. 119) that the ‘Research’ was 
more fortunate, and the hauls point to its having a distinct 
preference for the mesoplankton in the Faeroe Channel. Like 
(at any rate some) other mesoplanktonic species, it rises to the 
surface at night. Specimens with adult characters were captured 
in 19 per cent. of epiplankton hauls, but in 66 per cent. of meso- 
plankton hauls. On the other hand, larval and post-larval stages, 
apparently referable to this species, were obtained in 38 per cent. 
of epiplankton hauls, but only in one mesoplankton haul, and 
that one terminating near the 100 fathoms. The species, there- 
fore, appears to be epiplanktonic when young, mesoplanktonic 
when adult, so far as these observations go and in the Faeroe 
Channel at this time of year. In seeking deeper (colder) water 
in this locality, it follows what appears to be the practice of other 
Arctic type-forms when they meet the warmer water of the North 
Atlantic Drift. That this was not apparent from the results of 
the ‘ National’ is probably due to the fact that from the Hebrides 
almost up to the moment of coming into the Gulf-Stream the 
vessel was in far colder surface-water than that of the Faeroe 
Channel in summer. 
The larvee mentioned above ranged from an early Calyptopis 
stage up to the adult condition. It was not, of course, possible to 
derive them all with certainty from Thysanoessa longicaudata ; but 
the majority may be safely referred to this species, not only 
because the adults captured were far in excess of any other 
Kuphausid, but also because the larvee could be traced gradually 
through successive stages back to the Calyptopis. The meta- 
morphoses of this species follow the lines indicated by Sars * for 
Nyetiphanes, Huphausia, and Thysanopoda. 
As Paul Mayer* has shown, the spination of the telson of 
Malacostracan larvee yields a character important both for phylo- 
geny and for diagnosis. It has not as yet, I think, been pointed 
out that the condition of the telson’ in Huphaustid: affords a 
further argument for the view maintained by Boas’ and others, 
1 ©, Chun: ‘ Beziehungen zwischen dem arktischen und antarktischen Plankton,’ 
Stuttgart, 1897, 8vo, p. 30. 
2 Proc. Zool. Soc. 1898, p. 583. 
3G. O. Sars: Chall. Rep. Zool. xiii. (Schizopoda). 
4 P. Mayer: Jenaische Zeitschrift, xi. (1877), p. 246 et seqq. 
® J. E. V. Boas: Morphologisches Jahrbuch, viii. p. 485. 
Proc. Zoot. Soc.—1903, Vou. I. No. TX. 9 
