468 OLEVE, DIATOMS. 
pag. 39, P1. II, fig. 43) Strie 8 in 0,01 mm. on one half of the 
valve more approximate to the median line than on the other, 
and on this half interrupted. Length 0,095—0,05 mm. Valves 
sometimes arcuate. 
Cape Wankarema. Pl. 36, fig. 26, 30. 
"This variety seems to connect Nav. (Rhoikoneis) superba 
Cl. with N. transitans. 
N. Zostereti Grun. — More or less lanceolate. Strize slightly 
radiant, distinctly tranversely lineate; strie 5 to 12 in 0,0 
mm., more approximate at the ends. 
forma genuina (A. Schm. Atl. Pl. XLVII, fig. 42—44 with 
about 7 strige in 0,01 mm.). Specimens from Kara have 9 strize 
in 0,01 mm. Length 0,1 mm. Breadth 0,02 mm. 
var. acutvuscula Greg. (Pinn. acutiuscula Greg. T. M. Soc. 
IV, pag. 48, Pl. V, fig. 21) Strie about 11 in 0,01 mm. — Kara. 
(Length 0,06 mm. Br. 0,01 mm.) 
Nav. longa Greg. (1. c. fig. 18) with 5 str. in 0,01, may per- 
haps be regarded as a form of N. Zostereti, were not the median 
line described as generally twisted, which character seems to 
indicate that N. longa is a Scoliopleura. 
N. erosa Cl. — More or less elliptic, about 5 times longer 
than broad, tapering regularly from the middle to the ends. 
Strie coarse, 7!1/.—10 in 0,01 mm., transversely finely lineate, 
a little radiant, interrupted, so that they have the appearance 
of being composed of fragments. Central nodule surrounded 
by a small area. Length 0,1 mm. Breadth 0,02 mm. — Pl. 36, 
fig. 28. — Cape Wankarema. 
N. (Rhoikoneis) trigonocephala Cl. N. Sp. — Linear with pa- 
rallel sides and cuneate, sometimes protracted ends. WValves 
often arcuate. Strie coarse 10—12 in 0,01 mm., almost paral- 
lel, interrupted as in N. erosa, transversely lineate. Length 
0,05—0,065 mm. Breadth 0,01—0,012 mm. — P1. 36, fig. 29. — Cape 
Wankarema. 
N. asymmetrica Cl. N. Sp. — Elongated elliptic, 4—5 times 
longer than broad. Strige almost parallel, interrupted, 91/3 in 
0,01 mm., transversely lineate, on one half of the valve reaching 
the median line, on the other ending at some distance from 
it. Length 0,1 mm. Breadth 0,023 mm. — P1. 36, fig. 27. — Cape 
Wankarema. 
Perhaps an asymmetric variety af N. erosa. 
N. (Rhoikoneis) superba CI. Valves rhombic, arcuate (or 
sometimes straight), convex and concave valves being more or 
less different. Strize almost parallel, transversely lineate, on the 
