500 



0LE7E, DIATOMS. 



at right angles, about 10 in 0,oi mm. In the centre of the 

 valve is a large blank area, where the puncta are absent or 

 as erased. Length 0,o3 — 0,o5 mm. Breadth 0,012 — 0,ou mm. 

 — PI. 37, fig. 56. 



R. quarnerensis Grun. (Verb. 1862, PI. IV, fig. 24)? It 

 is with great hesitation I have determined the form PI. 

 37, fig. 53 as the above species. There is in the middle of 

 the area a faint trace of a median line and of a very indi- 

 stinct central nodule, from which characters the form may 

 approach the genus Glyphodesmus. The forme of the valve 

 is sometimes a little cuneate (a). 



R.? marginulata CI. & Grun. — Lanceolate with marginal 

 striae, 15 in 0,oi mm., surrounding an apparently structure-less 

 large area. Length 0,o42 mm. Breadth 0,oo9 mm. — PI. 37, 

 fig. 57. 



Mr. Grunow found the same species in gatherings from 

 the Seychells. According to Mr. Grunow the large area is 

 pervaded by the shallow continuation of the marginal striae 

 and has in the middle a median line, which I could not see 

 with my lenses. 



Trachysphenia austrdlis H. L. Smith. (Raphoneis australis 

 H. L. Sm. Am. Quarterl. M. J. 1878, pag. 14, PL III, fig. 6. 

 Tr. australis var. ? Aucklandica Grun. in Van Heurck Syn. 

 PI. XXXVII, fig. 1). The genus Trachysphenia was establish- 

 ed by Mr. Petit in 1877 (Diat. de Campbell pag. 32). The 

 Tr. aiistralis Petit 1. c. PI. V, fig 19, is large and has 6 puncta 

 in 0,01 mm. It seems then to be different from Raphoneis 

 australis H. L. Smith, which is 0,oi28 — 0,02i8 mm. in length and 

 has 12 puncta in 0,oi mm. The specimens from Labuan are 

 about 0,022 mm. in length and have 11 rows of puncta on 0,oi 

 mm. Similar forms have I seen in gatherings from Port Jackson. 

 The cuneate form of the valve does not seem to be a constant 

 characteristic, as I have found elliptic valves, to the sculpture 

 agreeing with the cuneate ones. Such a specimen, var. eUiptica 

 CI., has been figured on PI. 37, fig. 54. 



Synedra commutata var. s&ptentrionalis Grun. (Van Heurck 

 Syn. PL XL, fig. 5) Length 0,054 mm. Strise 13 in 0,oi mm. 



S. affinis'Ku.iz. — Strise 13 in 0,oi mm., area tolerably narrow. 



S. Hennedyana Greg. (Diat. of Clyde pag. 532, PL XIV, 

 fig. 108). 



S. crystallina var. Sniithii Grun. (Van Heurck Syn. PL 

 XLII, fig. 10). 



S. fulgens Grev. (Sm. Syn. 1, pag. 74, PL XII, fig. 103). 



