KOFOID : NEW SPECIES OF DINOFLAGELLATES. 183 



The postindentation is shallow, about 0.25 transdiameter in depth, and the 

 postmargin is squarish, with serrate fin. 



The girdle is very oblique, displaced its own width, has low anterior and 

 posterior lists, the latter decurrent on the left antapical. The furrow is 

 slightly impressed and bears a few transverse ribs. 



The plates are normal, the left intercalary being very small. The sutures 

 are marked by ribs which locally bear hyaline serrated lists. Plates porulate. 

 Reticulation lacking on specimen seen. 



Length, 148 /x; transdiameter, 105 /x. 



Station, 4724. 



Heterodinium longum, sp. nov. 



Plate 7, Fig. 44. 



A medium-sized species resembling H. rigdenae but more elongated, with 

 deeper postindentation and higher epitheca. It also resembles H. hindmar- 

 chi, but can be distinguished from it by its wider epitheca with straighter 

 sides and the absence of convergence in the antapicals. 



The body is elongated, its length 1.5 times its transdiameter, compressed 

 dorso-ventrally. The epitheca exceeds the hypotheca, its length being about 

 0.6 of the total length. It is compressed conical, with straight margins and 

 apical but little deflected to the right. The ventral area is squarish and de- 

 flected to the left with eccentric pit. 



The hypotheca is contracted more than the epitheca, is convex anteriorly 

 and concave posteriorly at the margins. The antapicals are pointed, stout, 

 divergent, and subequal, the left often larger. The postindentation is deep, 

 exceeding 0.5 of the altitude of the hypotheca. The postmargin is broadly 

 rounded, and the tips 0.5 of a transdiameter apart. 



The girdle is slightly oblique, displaced its own width, with slight anterior 

 ridge and deficient posterior list obsolete distally. The furrow is not im- 

 pressed and is more or less ribbed. 



The plates are normal, suture lines well defined. Plates porulate, with 

 coarse regular reticulations. 



Length, 93-125 /x ; transdiameter, 65-90 /x. 



Stations, 4732, 4734, 4742. 



Heterodinium obesum, sp. nov, 



Plate 8, Fig. 50. 



A minute species with spheroidal body, prominent apical horn, large hypo- 

 theca, and very unequal antapicals. 



The body is robust ; excluding all of the horns it is almost a sphere. The 

 total length is 1.3 times the transverse or the dorso-ventral diameter. The 

 epitheca is a low cone with slightly flaring base, nearly straight sides, 

 and apex displaced ventrally. The total altitude is 0.6 of its transdiameter, 



