VEGA-EXPEDITIONENS VETENSKAPLIGA ARBETEN. 499 
P-. orientale Grev. (I. M. S. XIV, pag. 77, PI: VII, fig. 1). 
'P. tesselatum Grev. (M. J. Vol. VII, pag. 208, Pl. X, fig. 7). 
P. pulchellum Grev. (M. J. VII, pag. 209, fig. 4—6). : 
P. costatum Grev. (Ed. N. Phil. Journ. XVIII, 1863, pag. 35, 
fig. 5—6). The structure of the valve consists of numerous, 
strong, transverse coste and fine strix, composed of puncta, 
2 to 3 between each pair of cost:e. 
Dimerogramma nminus Greg. (Diat. of Cl. pag. 495, P1. X, 
fig. 35). 
var. nana (Greg.). 
Raphoneis amphiceros Ehr. — In the Labuan material I have 
seen this species in an almost incredible number of varieties, 
of which some are described as distinct species, 
a. forma typica P1-37, fig. 52 a Van Heurck Syn. Pl. 
XXXVI, fig. 20—23. 
b. var. major Raphoneis lanceolata Ehb.? Length 0,015 
mm. Breadth 0,023 mm. Rows of punceta 7 in 0,01 mm. 
ec. var. triangularis. 
d. var. ceruciata = Amphitetras cruciata Jan & Rab. Hond. 
Diat. pag. 4, Pl. I, fig. 5. — Intermediate forms between a. and 
d. are common in the Labuan material. PI 37, fig. 52 b. 
Such an intermediate variety is Raph. amph. var. californica 
Grun. in Var Heurck Syn. XXXVI, fig. 24. 
e. var. pentagona. P1. 37, fig. 52. c intermediate between 
d. and e. 
f. var. Castracaner Grun. (Van Heurck Syn. PI. XXXVI, 
fig. 28) Labuan. 
R.2? bilineata Gr. & Ol. — Valve variable in the outline, 
generally lanceolate. Sculpture strong, parallel coste 7 in 
0,01 mm., which, according to Grunow, are delicately punctate. 
The coste are interrupted by strongly marked lines on both 
sides of the raphe. Length 0,025—0,054 mm. Breadth 0,008— 
0,012 Mmm. 
forma a. lancettula Gr. & CI. valve lanceolate — Pl. 37, fig. 
55, b. Labuan, Seychelles (Grun.). 
forma b. protracta Cl. valve with protracted ends, median 
raphe expanded to an area. Length 0,o48. Br. 0,o12 mm. — Pl. 
37, fig. 55 a. — Labuan, Seychells (Grun.). 
forma c. elliptica Grun. Valve elliptic — Seychells (Grun.) 
forma d. contracta Grun. Valve contracted in the middle. 
Seychells (Grun.). i 
R. maculata Cl. N. Sp. — Rhombic or lanceolate, covered 
with pearl-like puncta, arranged in rows, crossing each other 
