22 K Canadian Arctic Expedition, 1913-18 



neck, upon the distal part of which there commence two rows of small denticu- 

 lations pointing distally. These denticulations are evenly disposed, increasing 

 slightly and then diminishing in size, to be continued upon the proximal half 

 of the attenuating setiform process (Fig. 27). This delicate and regular serru- 

 lation is quite different from the coarse denticulation figured for Acartia tonsa, 

 where the teeth are few in number, the proximal largest. 



18. Tortanus discaudatus (I. C. Thompson and A. Scott, 1898). 



In Professor Herdman's traverses of the Atlantic, which have been referred 

 to under Eurytemora herdmani, he obtained another leading component of the 

 Gulf of St. Lawrence copepod plankton, namely, the present species. Whilst 

 in America he paid a visit to Puget Sound, where he carried out some dredging 

 and tow-netting. Amongst the more abundant forms in the Puget Sound 

 gatherings was this same species, new for the Atlantic and new for the Pacific.^ 

 It composes 50-75 per cent of the summer copepod plankton off Souris, Prince 

 Edward Island, and is very abundant off the Biological Station at St. Andrews, 

 N.B. 



Station 17 a, b, c. See Table XI. 



Station 18. See Table I. 



Station 20a. See Table IX. 



B. Cyclopoida, Etc. 

 19. Oithona similis Glaus, 1866. 



This small and slender species is apt to escape through the meshes of 

 ordinary tow-nets, but none the less it appears frequently in Mr. Johansen's 

 gatherings. Like Acartia longiremis, it is an Arctic form with a southern ex- 

 tension. 



Station 12 b, c. See under Acartia longiremis. 



Station 12 d. Same position, surface, 15 minutes, net number 4, June 30, 

 1913. Phytoplankton {Coscinodiscus, Peridinium, Rhizosolenia, chain algse), 

 Tintinnoids and Oithona. 



Station 21 a, b, c. Table II. 



Station 25 b, c. Table III. 



Station 27y 2. Table V. 



Station 29g 4. See under Euchaeta norvegica. 



Station 30 a. Table VIII. 



Station 40 c. Bernard harbour. Dolphin and Union strait, water depth 9 

 fathoms, three vertical hauls, to 3 fathoms, through hole in ice; net number 3, 

 June 7, 1915. 



Table XIII (Sta. 40c). 



Pseudocalaniis elongatus, immature 9 . 

 Oithona similis d'- 

 Cyclopina schneideri. 

 Harpacticus superfkxus (f . 

 Dactylopusia signata 9 . 



Station 40 d. Same locality, depth, and net, six vertical hauls through hole 

 in ice, to 5 fathoms, June 8, 1915. 



1 W. A. Herdman, I. C. Thompson, Andrew Scott: On the plankton collected continuously during 

 two traverses of the North Atlantic in the summer of 1897; with descriptions of new species of Copepoda; 

 and an Appendix on dredging in Puget Sound. Trans. Liverpool Biol. Soc. XII, pp. 33-90, pis. V-VIII, 

 Liverpool 1898. 



