468 OLEVE, DIATOMS. 



pag. 39, PI. II, fig. 43) Strise 8 in 0,oi 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,o5 mm. Valves 

 sometimes arcuate. 



Cape Wankarema. PI. 36, fig.' 26, 30. 



This variety seems to connect Nav. (Bhoihon&is) superha 

 CI. with N. transitans. 



N. Zostereti Grun. — More or less lanceolate. Strise slightly 

 radiant, distinctly tranversely lineate; strise 5 to 12 in 0,oi 

 mm., more approximate at the ends. 



forma genuina (A. Schm. Atl. PI. XL VII, fig. 42—44 with 

 about 7 striae in 0,oi mm.). Specimens from Kara have 9 stries 

 in 0,01 mm. Length 0,i mm. Breadth 0,o2 mm. 



var. acutiuscula Greg. (Pinn. acutiuscula Greg. T. M. Soc. 

 IV, pag. 48, PI. V, fig. 21) Strise about 11 in 0,oi mm. — Kara. 

 (Length 0,06 mm. Br. 0,oi mm.) 



Nav. longa Greg. (1. c. fig. 18) with 5 str. in 0,oi, 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 CI. — More or less elliptic, about 5 times longer 

 than broad, tapering regularly from the middle to the ends. 

 Strise coarse, 7 V2 — 10 in 0,oi 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,i mm. Breadth 0,02 mm. — PL 36, 

 fig. 28. — Cape Wankarema. 



N. (Rhoikoneis) trigonocephala CI. N. Sp. — Linear with pa- 

 rallel sides and cuneate, sometimes protracted ends. Valves 

 often arcuate. Strise coarse 10 — 12 in 0,oi mm., almost paral- 

 lel, interrupted as in N. erosa, transversely lineate. Length 

 0,05 — 0,065 mm. Breadth 0,oi — 0,oi2 mm. — PI. 36, fig. 29.* — Cape 

 Wankarema. 



N. asymmetrica CI. N. Sp. — Elongated elliptic, 4 — 5 times 

 longer than broad. Strise almost parallel, interrupted, 9 '/2 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,i mm. Breadth 0,023 mm. — PI. 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. Strise almost parallel, transversely lineate, on the 



