18F Canadian Arctic Expedition, 1913-18 
Melosira Westii W. Sm. 
Van Heurck Syn., PI. 91, figs. 11-12. 
Found only at Station 43), there rather plentiful. 
Navicula Bory 
Navicula abbreviata Grun. 
Cl. and Grun. Arct. Diat., Pl. 2, fig. 43. 
Found only at Station 438c, scarce. 
Navicula algida Grun. 
Diat. F. Jos. Land, Pl. 1, fig. 31. 
Found in dredgings from Stations 23 and 48a, and in a plankton haul from 
Station 299. 
Navicula aspera Ehr. 
Grun. Diat. F. Jos. Land, Pl. 1, fig. 20. 
This is by far the most abundant species found, some of the many varietal 
phases being present in nearly every gathering, often in great quantity. The 
most prominent form is the large variety called N. aspera var. intermedia Grun. 
and figured in the above reference. Especially common at Stations 23 and 27s. 
Navicula Baculus Cl. 
Cl. Vega Diat., Pl. 37, fig. 51. 
This should not be considered to be a variety of N. inconspicua Greg. Found 
only at Station 29g. 
Navicula Baileyana Grun. : 
Sch. Atlas, Pl. 6, figs. 26-27; Sch. Diat. Nordsee, Pl. 1, fig. 31. _ 
The type form occurs at Stations 20b-c and 23, and a variety at 23. 
Navicula bipustulata Mann, sp. nov. 
Pl. I, fig. 6; also Sch. Atlas, Pl. 46, fig. 67. 
Valve linear, quite convex, the rounded apices ending in globular tips; costae 
absent at the middle, thereby leaving a wide stauros, at first radial and strongly. 
bowed, becoming transverse and straight at the apices, very faintly cross barred; 
rhaphe median at the centre but becoming slightly lateral at the apices. 
Length 0-047 mm., width 0-008 mm., 8-5 lines in 0-01 mm. 
Possibly this is the same asthe unnamed figure in Sch. Atlas above, which 
subsequently Grunow suggests is a variety of N. cancellata Donk., to which it 
has practically no resemblance; see Donk. Brit. Diat., Pl. 8, fig. 4. Cleve 
accepts this with a varietal name, subapiculata. To illustrate the muddled 
group that Cleve unites under N. cancellata, compare N. truncata Donk. in 
Mic. Journ., 1861, Pl. 1, fig. 4a-b and N. retusa Donk. in fig. 17a-b same plate. 
When such dissimilar species are called by the same name diatom taxonomy 
loses all value. Found at Station 23. 
Navicula bomboides A. Sch. 
Sch. Atlas, Pl. 18, fig. 29. 
Found at Stations 20b-c and 43a. 
Navicula Bombus Ehr. 
Sch. Atlas, Pl. 13, figs. 5, 6, 9. 
Found only at Station 43a and rather scarce. 
Navicula brevis Greg. 
Sch. Diat. Nordsee, Pl. 2, figs. 14, 15. 
Found at Stations 20b-c, 23, 41, 41¢ and 48g. 
Navicula cancellata Donk. var. minuta Grun. 
Cl. and Grun. Arct. Diat., Pl. 2, fig. 42. 
This is hardly a good variety of N. cancellata. Found at Station 20b-c. 
