236 TJniversity of California Publications in Zoology. [Vol. 8 



transdiameters. The liypotheca has, in ventral view, a broadly rounded 

 postmargin whose even contour is interrupted by the asymmetry adjacent 

 to the base of the antapical spine. In lateral view it is a rather 

 abruptly contracted cone, especially on the ventral face. Its altitude 

 is 0.6 to 0.8 transdiameters. 



The girdle is postmedian, descending, displaced distally 1.5 to 3 girdle 

 widths, with a sharply curved proximal end, far more than in either 

 G. polygramma or G. pacifica, without overhang. Furrow relatively very 

 narrow, its width 0.1 to 0.05 transdiameters, very deeply impressed and 

 with projecting shelf-like ridges of thecal wall, which occasionally bear 

 very low lists. The ventral area or longitudinal furrow somewhat ob- 

 scured by asymmetrical ventral excavation in which it lies, is relatively 

 wide, gradually spreading posteriorly to four girdle widths. The ventral 

 area indents the epitheca with a slender extension of the anterior plate 

 with oblique end, and posteriorly the wide posterior plate broadly invades 

 the antapical plate. In some cases this end of the ventral area is at the 

 postmargin of the body. In others it Jies somewhat anterior to it so 

 that the antapical plate is exposed in the ventral view as in our figure. 

 The plate formula is 3', 0", 6", 6, 6'", IP, 1"". Ventral apical 1' is 

 very slender and is attached at the apex to a closing platelet. Apical 2' 

 is asymmetrically extended in the apical region in an apical lobe which 

 crowds in between the apex and the top of apical 3'. There is no apical 

 notch as in Spiraulax jollifei and the small inconspicuous ventral pore is 

 borne at the posterior corner of apical 3'. Precingular 6" is quadrilateral 

 its anterior margin being convex and about four girdle widths long. 

 Postcingular V" is very small, and the posterior intercalary very long and 

 narrow. The plates were not correctly interpreted in my earlier (1907) 

 description. The ventral area consists of a narrow anterior plate against 

 the lower half of which the furrow abuts, which is deeply notched pos- 

 teriorly by the flagellar pore. The large posterior plate has a broadly 

 rounded postmargin. Between these two plates there are at least three 

 plainly marked off intermediate plates, the anterior one of which is 

 notched by the flagellar pore. 



The surface is marked b,y striae which follow longitudinal suture lines 

 and occasionally transverse ones also, in bands of one to four closely 

 set parallel elements. They are better developed on the pre- and post- 

 cingular plates, are often incomplete and show a tendency to follow lines 

 of pores. Intercalary bands of varying width may follow the main 

 suture lines. The wall is generally rather thin and hyaline with minute, 

 sparsely distributed pores in rather vague lines. We have not seen 

 coarsely or heavily reticulated individuals, though faint reticulations are 

 sometimes present (pi. 15, fig. 35). The furrow is often heavily ribbed. 

 There are sometimes very low hyaline girdle lists and low denticulate 

 lists with abundant spinules arise from the sutures between the posterior 

 intercalary iP and the ventral area, and between the latter and the 

 antapical. The solid antapical spine is relatively short, from 1 to 3 

 girdle widths in length. It is tapering, sometimes finned on both sides 

 and arises from the left angle of the antapical plate. 



