180 



DEPARTMENT OF THE NATAL SERVICE 



It will be seen that the comparison of the vertical hauls is chiefly demonstrative of 

 the relative constancy in the character of the Calanoid fauna in the Laurentian 

 Channel from June to August. 



In order to obtain full value from these tables it is necessary to distinguish 

 between what may be called eurytropic species which are generally distributed through- 

 out the area covered by the several cruises, and stenotropic species whose distribution 

 is seemingly limited within a narrower range by physical factors of temperature, 

 salinity, and depth. Such eurytropic species are Calanus finmarchicus, Pseudocalanus 

 elongatus, Euchaeta norvegica, and Metridia longa. In consequence of their ready 

 toleration of slight changes in the temperature and saltness of the water these species 

 are not reliable indicators as regards the interaction of currents and the stratification 

 of the water. On the other hand the stenotropic species such as Calanus hyperboreu^, 

 Euchirella rostrata, Scolecithrix minor, Metridia lucens, and Heterorhahdus norvegicus, 

 are especially valuable as indicators. Thus the subjoined table shows that a greater 

 number of these stenotropic species occurs on the eastern side of Cabot strait in the 

 boreal oceanic water which is in the track of the inflowing Cape Eay current, than on 

 the western side in the line of the Cape Breton current which conveys water out of the 

 gulf of St. Lawrence. This agrees with the behaviour, in this region, of certain 

 species of Sagitta, as I am informed by Dr. A. G. Huntsman, who has made a most 

 intensive study of the distribution of the Chaetognaths and with whom I have discussed 

 the bearing of some of the data presented in this report concerning the Copepods. 



Table H. — Vertical hauls in Acadia stations 85 to 87, July 28, 1915. 



Laurentian Channel. 



Across 



Species. 



C. hyperboreus 



Calanus finmarchicus III. 

 IV . 



V . 

 9 . 

 cf . 



III. 

 TV 



V . 

 9 



Pseudocalanus elongatus . 



Aetideus armatus 



Gaidius tenuispinus 



Kuchirella rostrata 



ICuchaeta norvegica 



Scolecithrix niinor 



M ovata ....... 



Centropages haniatus 



Metridia longa 



II lucens 



Heterorhahdus norvegicus. 



270-0 metres. 

 85 



1 



25 

 15 



2 



5 



Ifi 



15 



100 



270-0 metres. 

 86 



X 

 10 

 34 

 10 

 10 

 X 



2 

 X 

 X 



2 

 X 



X 



22 



2 



100 



290-0 metres 

 87 



3 



10 



2S 



8 



1 



X 



1 



X 



X 



1 



X 

 X 

 X 

 26 

 1 

 X 

 X 

 20 

 1 



100 



Acadia stations 88 and 89, on Misaine bank, both yielded Euthemisto plankton, 

 including an abundance of C. finmarchicus from stage III to spawning females, with 

 an excess of stage IV in all the hauls. On this bank at the beginning of June we 

 encountered an Aglantha plankton, whereas at the end of July there were no medusas 

 here. As regards the Calanus, the chief change to be noticed was an increase in the 

 number of adult females, 26 per cent in each of the surface hauls at stations 88 and 

 89. The latter station may be compared with station 79. Finally, at station 91 in the 

 Gut of Canso there was an Evadne plankton with a copepod admixture consisting of 



