36 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



6. P. galapageuse Cl. N. Sp. — V. scarcely sigmoid, lanceolate, tapering from the middle 

 to the subacute ends. L. 0,17; B. 0,o46 mm. Median line straight, central. Transv. and obi. striae 

 I'/u in 0,01 mm. Angle about 90°. — PI. IV f. 16. 



Marine : G-alapagos Islands ! 



This form is nearly akin to P. nicobaricum, but differs by the median ^ striae, which are not 

 more distant than the terminal. 



7. P. Eudon Pant. (1886). — V. scarcely sigmoid, lanceolate, tapering from the middle to 

 the subacute ends. L. 0,28; B. 0,05 mm. Median line straight, central. Transv. and obi. striae 

 'Vij (on the fig. in Pant.). Ends of the valve with a lunate marking. — Pant. I p. 30 PL XXI 

 f. 190. Per. Ill f. 21. 



Marine: Hungary, fossil (Pant.). 



8. P. nicobaricum Geun. (1867). — V. scarcely sigmoid, lanceolate, gradually tapering from 

 the middle to the subacute ends. L. 0,14; B. 0,035 to 0,04 mm. Median line central, straight. 

 Obliqiie striae more distant in the middle. Transverse striae coarser than the oblique (15 to 16 in 

 0,01 mm. according to Grun.). Transv. and obi. striae '■^720 in 0,oi mm. (Perag.). Median oblique 

 striae 20, terminal 24 in 0,5 1 mm. (Perag.). — P. validum var.? nicob. Grun. Novara p. 101 PL I. 

 A. f. 20. P. nicobar. Grun. A. D. p. 51. Per. p. 10 PL IV f. 9. P. afftne var. nieob. Grun. in 

 V. H. Syn. Suppl. PL C. f. 34. 



Marine: Nankoori, fossil (Grun.), Belgium (V. H.). 



Var. Sagitta Brun. and Temp. (1889). — V. rhombic-lanceolate. L. 0,i5 to 0,175; B. 0,03 

 to 0,036 mm. Median oblique striae 12 to 14, terminal 17 to 20 in 0,oi mm. (Brun.). — P. Sagitta 

 Brun. and Temp. D. foss. du Japon p. 49 PL IX £ 19. Per. IV f. 13. 



Marine: Japan, foss. (Brun.). 



Var. hamulifera Brun. (1889). — V. rhomboidal. L. 0,o9 to 0,12; B. 0,025 to 0,03 mm. 

 Median line central, straight, curved at the ends. Median oblique striae more distant than the 

 terminal striae which are at an acuter angle. Transv. and obi. striae ^721 (21 to 24 Brun) in 0,o 1 

 mm. — P. hamuliferum Brun. D. foss. du Japon p. 48 PL IX f. 5. Pee. p. 13 PL V f 31. P. 

 nicob. var. indica Per. IV f. 12. 



Marine: Japan (Brun.), China (Deby Coll.)! Sumatra (Per). 



The original P. nicobaricum greatly resembles my P. galapaginse, but accot-ding to Grunow 

 (A. D.) it is nearly akin to P. affine and the fig. in V. H. Syn. evidently represents a form akin 

 to P. Normanii. This is also the case with P. Sagitta Brun. As to P. hamuliferum I have not 

 seen Brun's original specimens, and his description of the striation is incomplete. In Deby's collec- 

 tion I have seen a specimen closely resembling P. hamuliferum and evidently nearly akin to P. 

 Normanii. It closely resembles P. nicob. var. indica Per. It seems probable that the original P. nico- 

 baricum may be identical with P. galapagense, and that P. nicob. Grun. in V. H. Syn., Per, gra- 

 duates into P. Normanii. 



9. P. naviculaceum Br^b. (1854). — V. not, or slightly sigmoid, lanceolate, acute. L. 0,o8 

 0,1; B. 0,015 to 0,02 mm. Median line strongly sigmoid. Median oblique striae more distant than 

 the terminal, 'w'hich are at an acuter angle. Transv. and obi. striae 'Vi6> "/i7> ^Vis- — P-navic. Br^b. 

 Mem. de la Soc. du Cherb. 1854 f. 7. Grun. A. D. p. 51. V. H. Syn. Suppl. PL C. f. 35. P. 

 transversale W. Sm. B. D. II p. 96 (1856). P. japonicum Castr. D. Challenger Ex. XXIX f. 14. 



Marine: North Sea! Mediterranean! Ceylon! Java! Labuan! 



Forma minuta. L. — 0,05; B. 0,oi5 mm. Transv. and obi. striae 22/^^. 



Marine: Sumatra! Bab el Mandeb.! 



10. P. hungarieum Brun. and Cl. (1889). — V. broadly rhomboidal, slightly sigmoid, acute. 

 L. 0,1 to 0,13; B. 0,04 5 to 0,0 6 mm. Median line strongly sigmoid. Central nodule orbicular. 

 Median oblique striae forming a larger angle than the terminal, which are more acute. Transv. 



