24F Canadian Arctic Expedition, 1913-18 
Navicuila vetula A. Sch. var (?) 
Pl. I, fig. 11. Compare Sch. Atlas, Pl. 69, fig. 33, and Pl. 12, fig. 49. 
Although this diatom agrees with the above in general outline, in the 
longitudinal division of the markings and in the rhaphe area, it appears to be a 
coarser form. It also is about the same size as the smaller of the two figures of 
Schmidt. Cleve in Nav. Diat., I, p. 85, gives for the larger figure above the 
following: length 0-05 mm., width 0-024 mm., 10 lines in 0-01 mm.; my speci- 
men gives length 0-032 mm., width 0-016 mm.; 6 lines in 0:01 mm. A new 
name may be needed for this form. Found at Station 23. 
Nitzschia Hass. 
Nitzschia acuta Hantz. , 
Sch. Atlas, Pl. 334, figs. 25-26. } 
Found only at Station 27s, there frequent. 
Nitzschia distans Greg. 
Greg. Diat. Clyde, Pl. 14, fig. 1083; Van Heurck Syn., Pl. 62, figs. 10, 18. 
Found only at Station 23. 
Nitzschia hungarica Grun. 
Van Heurck Syn., Pl. 58, figs. 19-22. 
Although usually fresh-water it inhabits brackish localities and is listed in 
Cleve’s Arct. Diat. Found at Station 27s, frequent there. 
Nitzschia hybrida Grun. 
Van Heurck Syn., Pl. 60, fig. 4; Cl. and Grun. Arct. Diat., Pl. 5, fig. 95. 
Found at Station 43c, two gatherings. 
Nitzschia incurva Grun. 
Van Heurck Syn., Pl. 70, figs. 13-14. 
As Van Heurck intimates, this may be a variety of N. Lorenziana Grun. 
See fig. 12 same plate. Found at Station 20b-c. 
Nitzschia insignis Greg. 
Van Heurck Syn., Pl. 61, fig. 1; Perag. Diat. France, Pl. 75, figs. 3-12. 
Found rather frequently in material from Stations 23, 41, 48a and 43c. 
Nitzschia linearis (Ag.) W. Sm. 
Sm. Brit. Diat., Pl. 13, fig. 110. 
Found at Stations 23 and 27s. 
Nitzschia littorea Grun. 
Van Heurck Syn., Pl. 59, figs. 21, 25. 
It is questionable if anything is gained by uniting this with N. thermalis 
(Kitz.) Grun., as is suggested above; compare fig. 20 of the same plate. 
Nitzschia longissima (Breb.) Ralfs. 
Van Heurck Syn., Pl. 70, figs. 1-4. 
Nearly all specimens were very small and delicate, like fig. 3 above. Cleve 
and Grunow record this from the Arctic. Found at Stations 20b-c and 43c. 
Nitzschia marginulata Grun. 
Van Heurck Syn., Pl. 58, figs. 12-15. 
Found at Stations 20b-c, 48 b and 48 c. 
Nitzschia plana W. Sm. 
W. Sm. Brit. Diat., Pl. 15, fig. 114; Van Heurck Syn., Pl. 58, fig. 10. 
Scarce and not quite typical; found at Station 23. 
