28 F Canadian Arctic Expedition, 1918-18 
Stauroneis Ebr. 
Stauroneis anceps Ehr. 
Van Heurck Syn., Pl. 4, figs. 4-5. ; ; ; 
Although the members of this genus belong in reality to N. avicula the 
generic name Stauroneis is retained by most authors for convenience, but not as 
indicating a scientific generic division. Beach at Bernard harbour, July 15, 1915. 
Stauroneis spicula Dickie. 
Perag. Diat. France, Pl. 7, fig. 30. 
Found at Station 27s, scarce. 
Surirella Turp. 
Surirella folialifera Mann, sp. nov. 
PL. I, fig. 13. a 
Valve broad, ovate, robust; rim massive, winged; costae beginning at the 
margin in leaf-shaped plates, which are strongly striped longitudinally, and 
from the inner ends of which the costae extend as narrow lines or ridges to the 
inconspicuous median area; polar space at the blunt end of the value evident. 
Length 0-056 mm., width 0-033 mm. Only two specimens found, at 
Station 20b-c. 
Surirella insignis Ostr. 
Ostr. Diat. N.E. Greenland, p. 216, Pl. 18, fig. 19; Sch. Atlas, Pl. 21, fig. 15, 
no name. . 
This species seems to be rare. Several fine specimens were found, Station 
23, in two gatherings. 
Surirella striatula Turp. 
Sch. Atlas, Pl. 24, figs. 18, 20-21; Van Heurck Syn., Pl. 72, figs. 5-6. 
Scarce, Station 43g; usually a very prolific species. 
Synedra Ehr. 
Synedra affinis Kiitz. var. gracilis (Kitz.) Grun. 
Van Heurck Syn., Pl. 41, fig. 150. 
Found at Stations 20b-c and 436, abundant in both. 
Synedra arctica Grun. (not O’Me.). 
Grun. Oster. Diat., p. 401, Pl. 8, fig. 3. 
Average length of my specimens 0-099 mm., average width 0-004 mm. 
Found in plankton haul at Station 43f. 
Synedra kamtschatica Grun. (?) 
Cl. and Grun. Arct. Diat., Pl. 6, figs. 111-113. 
My specimens have the wide hyaline space at the middle and agree in 
general with the above, except that the marginal lines are much shorter. They 
are similar to ‘‘Thalassionema gelida Perag.” in Perag. Antarct. Exp. France, 
Pl. 3, fig. 10, which is a Synedra. Very common at Station 20g. 
Synedra pulchella Kitz. 
Van Heurck Syn., Pl. 41, figs. 1-5. 
The species is normally fresh-water, sometimes brackish. Found abundant 
at Station 23. 
Thalassiosira Cl. 
Thalassiosira gravida Cl. 
Gran. Nord. Plankt., p. 18, fig. 12. 
Found in plankton hauls at Stations 6b, 12d, 18d and 25b-c, common in all, 
2specially the last. 
