YEGA-KXPEDITIONENS V ETEN S KAPLIG A AliBETEN. 



499 



P. orimtaU Grev. (T. M. S. XIV, pag. 77, PI. VIII, fig. 1). 



P. tesselatum Grev. (M. J. Vol. VII, pag. 208, PI. 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 costse and fine strise, composed of puncta, 

 2 to 3 between each pair of costee. 



Dimerogramma minus Greg. (Diat. of CI. pag. 495, PI. X, 

 fig. 35). 



var. nana (Greg.). 



RapJioneis 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 PI. 37, fig. 52 a. Van Heurck Syn. PI. 

 XXXVI, fig. 20—23. 



b. var. major Raphoneis lanceolata Ehb.? Length 0,075 

 mm. Breadth 0,o23 mm. Rows of puncta 7 in 0,oi mm. 



c. var. triangularis. 



a. var. cruciata = 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 Van Heurck Syn. XXXVI, fig. 24. 



e. var. pentagona. PI. 37, fig. 52. c intermediate between 

 d. and e. 



f. var. Castracanei Grun. (Van Heurck Syn. PL XXXVI, 

 fig. 28) Labuan. 



R.? bilineata Gr. & CI. — Valve' variable in the outline, 

 generally lanceolate. Sculpture strong, parallel costse 7 in 

 0,01 mm., which, according to Grunow, are delicately punctate. 

 The costse are interrupted by strongly marked lines on both 

 sides of the raphe. Length 0,o2o — 0,o64 mm. Breadth 0,oo8 — 

 0,012 mm. 



forma a. lancettula Gr. & CI. valve lanceolate — PL 37, fig. 

 55, b. Labuan, Seychelles (Grun.). 



forma b. protracta CI. valve with protracted ends, median 

 raphe expanded to an area. Length 0,o4s. Br. 0,oi2 mm. — PL 

 37, fig. 55 a. — Labuan, Seychells (Grun.). 



forma c. dliptica Grun. Valve elliptic ■ — Seychells (Grun.) 



forma d. contrada Grun. Valve contracted in the middle. 

 Seychells (Grun.). 



R. maculata CI. N. Sp. — Rhombic or lanceolate, covered 

 with pearl-like puncta, arranged in rows, crossing each other 



