SK Canadian Arctic Expedition, 1913-18 



4. Pseudocalanus elongatus (Boeck, 1864). 



This species shares with Acartia the quality of being the most abundantly 

 represented in Mr. Johansen's gatherings. In addition to the stations tabulated 

 above, the following have to be added. 



Station 130, h: 54 30' N., 159 42' W., two surface tows of 15 and :*<) 

 minutes, net number 3, July 1, 1913. The gathering was very scanty, a female 

 Pseudocalanus being present, together with traces of Metridia, Acartia, Har- 

 pacticus, and Cypris-l&rvsd of Cirripedes. 



Station 20a: Grantley harbour, Alaska; depth two fathoms, surface tow 

 .") minutes, net number 3, July 30, 1913. This was a Cladoceran plankton, 

 numerous Evadne and Podon, with strong copepod infiltration, and some Mollus- 

 ran and Annelid larvae. Acartia clausi was almost as abundant as were the 

 Cladocera. 



TABLE IX (STA. 20a). 



I'm udocalanus elongatus, scarce; o", 9 and young. 

 Centropages mcmurrichi, abundant; 9 and somecf. 

 Eurytemora herdmani, two ovigerous females. 

 Eurytemora johanseni, males only noted. 

 Acartia clausi, very abundant. 

 Tortanus discaudatus, one female. 

 Idycea furcata, one female. 



Station 40d: Bernard harbour, water depth 9 fathoms, six. vertical hauls 

 0-5 fathoms with net number 3 through hole in ice, June 8, 1915. Female and 

 immature male, the latter with four-jointed urosome but anterior antennae 

 19-jointed as in adult male. 



Station 42p: Bernard harbour (outer harbour), surface tow with net 

 number 3 for 10 minutes, September 30, 1915. The scanty gathering included 

 a few Pseudocalanus, mostly young. There were also present: Eurytemora 

 herdmani <?, Oithona similis, Harpacticus uniremis, Idycea furcata, Danielssenia 

 stefanssoni. 



Station 42y: Dolphin and Union strait, off Bernard harbour, depth 17 

 feet; ice 2J feet thick, December 6, 1915, time noon. Six vertical hauls from sur- 

 face to bottom were taken with net number 3 at low tide with an eastward 

 current. There were upwards of 100 small copepods. The Pseudocalanus 

 were of various ages, abdomen two to fourjointed, all immature. 



TABLE X (STA. 42y). 



Pseudocalanus elongatus . . .'. 40 



Metridia longa , 8 



Acartia longiremis 2 



Oithona similis 38 



Onccea conifera 2 



Idycea furcata 10 



100 



Station 422: Same locality and depth as preceding; time midnight; three 

 vertical hauls with net number 3 from bottom to surface through hole in ice; 

 water temperature 29-2 F., December 12, 1915. Both males and females were 

 taken, in company with Idycea furcata, Metridia longa, Acartia longiremis, Oncaea 

 conifera and Thaumaleus bernardensis. 



A female Pseudocalanus from station 27t, u, (above table IV) had a two- 

 chambered cyst attached to the right anterior antenna, with faint indication 

 of radial arrangement of the brown granular contents (Fig. 1). Similar parasites, 

 questionably assigned to the Infusoria, were observed and figured upon Calanus 



