178 BULLETIN : MUSEUM OF COMPAEATIVE ZOOLOGY. 



Heterodinium curvatum, sp. nov. 



Plate 8, Fig. 48. 



A large species with tapering epitheca deflected to the right, salient girdle, 

 widely separated spreading antapicals with slightly incurved tips. 



Body elongated, length nearly twice the transdiameter at the girdle, and 

 nearly three times the greatest dorso-ventral extension. Epitheca contracted 

 regularly from the base to the apical pore. Right margin somewhat concave, 

 the left nearly straight, a feebly developed apical horn inclined to the right. 

 Altitude about equals the transdiameter. Ventral area squarish, pit nearly 

 central. 



Hypotheca shorter than epitheca on ventral face, equal to it on the dorsal. 

 Its altitude less than a transdiameter. More abruptly contracted than the 

 epitheca to the base of the antapicals, which diverge but have incurved tips. 

 Distance between the tips 0.6 of a transdiameter. Postindentation moderate, 

 axial depth 0.4 of a transdiameter, the postmargin a very broad curve. Antap- 

 icals subequal, elongated, tapering, acute. 



Girdle oblique, displaced its own width, obsolete distally, its posterior list 

 decurrent on the right antapical. Furrow deeply impressed, with salient ridges 

 partially reticulate. 



Thecal plates normal ; sutures marked by smooth bands, or bands of minute 

 polygons. Lateral sutures with high lists. Reticulations somewhat deficient 

 on tips of apical and antapical horns and midcentral region of hypotheca. 

 Reticulations relatively small, porulate, subequal, elongated and subregular 

 along the lateral margins. About 150 reticulations on the dorsal apical plate 

 and 34 contiguous to the girdle on the dorsal side. 



Length, 235 ft ; transdiameter, 127 ;*. 



Station, 4699. 



Heterodinium expansum, sp. nov. 



Plate 6, Fig. 36. 



A small species with short, stout, widely separated antapicals, nearly straight 

 postmargin, and very oblique girdle. 



The body is stout, its length being 1.3 transdiameters. It is strongly flat- 

 tened dorso-ventrally, its greatest dorso-ventral extension being only 0.28 of a 

 transdiameter. The girdle is very oblique, its antero-posterior extension being 

 0.3 of the total length. It is nearly median in position. 



The epitheca is broadly rounded anteriorly in ventral view and passes 

 abruptly into the short apical horn, which is deflected a little to the right 

 and ventrally. Its altitude is 0.6 of a transdiameter and its ventral face 

 flattened. The ventral area forms an elongated tract in the centre of the 

 ventral face, and the ventral pit is located anteriorly in this area. 



The hypotheca is convex laterally, excavated ventrally, with short, stout, 

 acute, subequal antapical horns 0. 18 of a transdiameter in length. The post- 



