354 University of California Publications. [ ZooLocy 
Heterodinium triacantha (Jirg). 
Gonyaulax (?) triacantha Jorgensen (799), p. 35. 
Ceratium hyperboreum Cleve (’00), pp. 14-15, Pl. 8, fig. 5. 
Gonyaulax triacantha, Paulsen (’04), pp. 21-22, fig. 5. 
This form appears to belong to Heterodinium by reason of 
the reticulated thecal wall, the midventral suture of the epitheca 
deflected to the left, the widened distal end of the transverse 
furrow, and the longer right antapical spine. There is also 
some indication that the distal end of the posterior list of the 
girdle is continued in the suture on the right side of the hy- 
potheca. None of the figures shows the ventral area or pit, or 
the theeal plates in full. In so far as they are indicated in Paul- 
sen’s (’04) figures, they conform to those of the genus Hetero- 
dinium. There are difficulties in reconciling Cleve’s (’00) figures 
with each other, and with those of Paulsen (’04) as well as with 
Jérgensen’s description, probably due to the fact, that, as Paul- 
sen suggests; Cleve’s figure is reversed, 7.e., it is a view of the 
ventral face as viewed through the body from the dorsal face. 
This species probably belongs in the subgenus Sphaerodimum, 
though it does not possess a spheroidal body. It is characterized 
by the absence of antapical horns and post indentation, concave 
sides of the epitheca, the developed apical horn, and the three 
antapical spines. 
Dimensions :—length, 72-84; transdiameter, about 50,; 
dorsal-ventral, about 45p. 
Reported from coasts of Norway and Iceland. 
Heterodinium inaequale sp. nov. 
[EAL ibs mates Sh Alo) 
This is a small subpentagonal species with rotund epitheca 
and unequal widely separated antapicals. 
The body in face view is subpentagonal, the two anterior mar- 
gins are quite convex, the left posterior nearly straight, the right 
slightly convex and the postmargin between bases of the antap- 
icals is coneave. The length is 1.2 and the dorso-ventral diam- 
eter 0.75 times the transdiameter. The epitheca is low dome- 
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