230 University of California Publications in Zoology. [Vol.8 



ing longitudinal furrow, usually with two or more short unequal 

 antapical spines, rarely but one or none ; theca with three apieals 

 and no intercalary and ten to fifteen longitudinal striae. 



Description: Body elongated, its length 1.5 to 2 transdiameters, sub- 

 circular in cross-section at the girdle, flattened ventrally. Epitheca ex- 

 ceeds hypotheca. Epitheca subconical, broadly angled at apical-precingular 

 suture, its altitude 0.6 to 0.95 transdiameters, contracted to a stout apical 

 horn one girdle width across and one to two in height. Hypotheca 

 broadly and symmetrically rounded, its altitude 0.5-0.6 transdiameters. 

 Girdle postmedian, descending, displaced distally 0.1 to 1.5, or even 2, 

 girdle widths, with very little overhang if any; furrow deeply impressed 

 with stout ridges, rarely with very low lists. Ventral area on longitudinal 

 furrow widening on the right distally to 2 girdle widths, very narrow 

 between girdle ends. The anterior plate {ant. ph, pi. 10, fig. 7) of the 

 ventral area indents the epitheca somewhat more than a girdle width, and 

 is squarely truncate anteriorly. 



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

 is slender, widening posteriorly on the left, slightly excavated. It is 

 attached to the elliptical closing platelet {cl. pi., pi. 10, fig. 7), which 

 contains an elongated hyaline area. Apieals 2' and 3' are wide plates, 

 the anterior dorsal angle of 2' being continued in a small point to the 

 right (pi. 10, fig. 6). The upper end of apical 3' sometimes has a small 

 pore-free area set off from the rest of the plate by a well-marked 

 oblique curved rib, as in G. spinifera. The area thus enclosed cor- 

 responds in position and relationships to a larger area in G. areolata and 

 to the small separable apical plate in G. diegensi.^. It is not in our 

 experience, separable in G. polygramma. It might be regarded as an 

 incipient plate, the separation of which in G. polyedra and G. diegensi.^ 

 is fully realized. There is no ventral notch, but the ventral pore (v. po.) 

 can usually be found on the median margin of 3' a short distance above 

 the apical-precingular suture. It is sometimes a mere notch in the mar- 

 gin of the plate. Precingular 6" is quadrangular, its anterior face being 

 nearly two girdle widths across. Postcingular 1'" is very narrow, over- 

 hanging the furrow. The posterior intercalary is very large, two girdle 

 widths across, and the antapical 1"" relatively small, and indented by 

 the rounded end of the ventral area. This area has its anterior plate 

 (ant. pi.) deeply notched for the flagellar 2:)ore and its posterior plate 

 broadly rounded posteriorly. Between the two the four or five narrow 

 subdivisions of the intermediate plate (int. pi., pi. 10, fig. 7) can be 

 made out in some specimens. 



The surface of the theca is very characteristically marked by a series 

 of 10-15 linear ridges with subparallel longitudinal arrangement, con- 

 tinued from one plate through the next and across the girdle from 

 epitheca into hypotheca with more or less continuity. The ventral 

 area and the posterior intercalary plate are not thus marked. Lemmer- 

 mann's (1907) statement that in his G. steini (^G. polygramma var. 

 Stein) "Zwischenplatten zahlreich " is doubtless based upon a miscon- 

 ception of the relation of these striae to suture lines. The intermediate 



