580 DB. G. H. FOWLER ON THE [June 21, 



The table on pp. 542-3 showing the vertical distribution of the 

 ' Research ' Copepoda in the Faeroe Channel, seems to me to offer 

 convincing proof of the existence of a living Mesoplankton. If 

 the forms which I caught at great depths were all dead, there 

 would be more dead species in the district than live ones, which 

 seems absurd ; the average number of species per haul is *88 in 

 the Epiplankton and 1'3S in the Mesoplankton. Further, the deep 

 water would contain an abundance of dead specimens of a species, 

 such as Eucliceta norvegica, of which there were practically no 

 specimens at the surface to be killed ; which also seems absurd. 

 Again, if the destruction at the surface is so extensive as the death- 

 hypothesis would imply, some specimens at least of Temora lonyi- 

 cornis, and of all such forms as are abundant at the surface, ought 

 to be captured in the lower strata ; yet this species was not onpe 

 taken in the Mesoplankton. 



In concluding this discussion of the general question, I would 

 strongly urge that any attempt, seriously to investigate the Meso- 

 plankton in future, should be made, not at random stations all over 

 the ocean, but in a limited area, one which presents as far as pos- 

 sible uniform conditions throughout, and may be presumed to 

 contain a similar fauna throughout ; for only by numerous successive 

 hauls at all depths can that careful comparison be made, which will 

 enable the observer to assign to each organism the proper signifi- 

 cance of its occurrences. 



DOLIOLUM (DoLioLETTA Borgert ') TKITONIS, Herdm. 

 = D. denticulatum Herdman 2 . 



This species presented no new anatomical features for record. 

 As Herdman points out 2 , some specimens are cylindrical rather 

 than of the characteristic barrel-shape ; he assigns this to imperfect 

 preservation. A comparison of my specimens from different 

 stations with specimens of other animals from those stations, leads 

 me to believe that the alteration in shape is due to damage in the 

 tow-net by pressure. The smallest sexual specimens which still 

 carried the stalk of attachment to the " Pnegethier " were about 

 5 mm. ; it had been lost in one of 7 mm. length. 



The horizontal distribution of this species was enormously ex- 

 tended by the ' National' (Plankton Expedition) ; till 1889 it had, 

 I believe, only been taken in the Faeroe Channel, the North Sea, 

 and off the Hebrides ; the ' National ' captured it in that year over 

 nearly the whole of their course, from the Labrador Current right 

 down to the South Equatorial Drift. 



The appearance of huge swarms of sexual forms of D. iritonis 



1 A. Borgert; Thaliacea der Plankton Expedition. C. Vertheilung der 

 Doliolen. 1894. 



W. A. Herdman : Trans. Roy. Sue. Edinburgh, xxxii. p. 101, 



