Vou. 2] Kofoid—On Heterodinium. 361 
Heterodinium whittingae sp. nov. 
TeAb ley aaweys alaleals}. 
A large species with very oblique girdle, elliptical outline, 
and shallow rounded bifureation. Body elliptical in face view 
with broadly rounded apical end and short incurved antapical 
_ horns which preserve the elliptical outline. The posterior bifur- 
cation extends but one-fourth of the distance to the girdle and is 
broadly rounded anteriorly. The body is very much compressed 
dorso-ventrally, forming a sharp edge at the lateral margins. 
The girdle is very oblique being inclined at an angle of 45° to 
the main axis in an antero-dorsal to postero-ventral direction. 
The length is 1.4 transdiameters and 3 times the distance 
between the greatest dorsal and ventral extensions which is found 
in the left half of the epitheca. The whole body is slightly 
twisted in a right spiral. 
The epitheca is very much flattened anteriorly and somewhat 
excavated on the ventral face, forming in fact a thin sheet which 
expands posteriorly as it meets the oblique girdle. The hypotheca 
is likewise flattened and excavated ventrally about the longitud- 
inal furrow. The lateral postmedian plates form a posteriorly 
projecting tooth on the left margin. 
The girdle forms a descending right spiral with slight dis- 
placement equalling its width. Its distal end is much widened, 
the posterior border becoming low and deflected posteriorly into 
the ventral suture of the right antapical horn. The longitudinal 
furrow is short and narrow. The flagellar pore is found as an 
elliptical opening at its proximal end. 
The thecal wall is thin, delicate and hyaline with hght suture 
ridges except in the case of the lateral sutures between the apicals 
which are doubled and heavy, as are also the lateral sutures on 
the hypotheca. The plates are normal, the left intercalary being 
restricted to the dorsal face. The surface, including that of 
the girdle plate, is everywhere covered with a reticulum of irreg- 
ular polygons, each with a single central pore. In the several 
specimens thus far observed the reticulum has been very hght 
and delicate. The polygons are relatively numerous, 97 having 
been recorded on the dorsal apical plate. 
