Marine Diatoms TF 
43a: Off Cockburn point. Lat. 68° 47’ N., long. nearly 115° W. Sept. 13, 
1915. 4-foot beam-trawl. for 1 hour. About 50 fathoms of water, 
sandy mud with pebbles. 
43b: Same as 43a. Sept. 14, 1915, and off Stapylton bay, 25-30 fathoms, 30 
minutes trawling. 
43e: West of Cockburn point, Sept. 14, 1915. 10-15 fathoms, sandy mud 
with many stones; 4-foot beam-trawl and 2’ x 4’ square dredge for 1 hour. 
43d: Locality and date as 43b. 
43f: Locality and date as 43c. : 
439: Bernard harbour, cuter harbour. Oct. 30, 1915. Bottom sample; 
sandy mud. 
46b: Off Bernard harbour, same locality as 422, but on February 5, 1916. 
50b: Stapylton bay, off Young point, N.W.T., Lat. 68° 55’ N. long., 116° 
52’ W., July 17, 1916, about 10 fathoms of water. Plankton-net 
No. 3 at surface. ‘ 
LIST OF SPECIES AND SYSTEMATIC DISCUSSIONS 
Achnanthes Bory 
Achnanthes arctica (Cl.) Mann 
Cleve Arct. Diat., Pl 4, fig. 22. 
It is called Achnanthidium arcticum in the above reference. Cleve changes 
it into a variety of Achnanthes brevipes Ag. in Nav. Diat., II, p. 194, a doubtful 
assignment. Specimens were found in dredgings made at Stations 23 and 43a. 
Achnanthes brevipes Ag. 
Van Heurck Syn., Pl. 26, figs. 10-12. 
Especially abundant in a dredging made in Dolphin and Union strait west 
of Cockburn point, Sept., 1915, Station 438c. 
Achnanthes hyperborea Grun. 
Grun. Diat. F. Jos. Land, Pl. 1, figs. 4-5. 
Found in a dredging made at Station 430. 
Achnanthes parvula Kitz. 
Van Heurck Syn., Pl. 26, figs. 25-28. 
Found with the foregoing. 
Achnanthes rhombica Ostr., var. 
Pl. I, figs. 1-2; Ostr. Diat. N.E. Greenland, p. 215, Pl. 13, fig. 18. 
My specimen agrees in general with this little known species, an illustration 
of which is here given, because the type figure differs somewhat and is in an 
obscure publication. The chief differences are that in my specimen there is no 
central hyaline area on the lower valve and its costae are far less flaring at the 
center; the form also is less angular. Incidentally my specimen is larger; 
length 0-041, width 0-014, 8-6 lines in 0-01 mm. (Ostrup’s specimen having, 
length 0-034, width 0-012, 11 lines in 0-01 mm.). One specimen, Station 41, 
plankton haul. . 
Achnanthes subsessilis Kitz. 
Van Heurck Syn., Pl. 26, figs. 21-24. 
Found rather abundantly at Stations 23 and 48a. 
