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



distant on the depressions (8 in 0,oi mm.) than towards the margin and the median line (18 in 

 0,01 mm.). — Diatomiste I p. 67 PI. X f. 10. 



Marine: Macassar Straits! 



This form is perhaps to be considered as a distinct species. 



49. N. impressa Grun. (1875). — V. elliptic-lanceolate. L. 0,o6 to 0,075; B. 0,o34 to0,045 

 ram. Axial area indistinct, central area small. Strise 7 to 9 in 0,oi mm. parallel in the middle, 

 slightly radiate at the ends. Puneta coarse, 7 to 11 in 0,oi mm. On both sides of the median 

 line are large Innate depressions. — A. S. Atl. VI f. 17, 18. 



Marine: Campeachy Bay! Sumbava (Kinker Coll.)! 



50. N. sparsipnnctiita Grove and Sturt (1886). — V. broadly elliptical, with rounded ends. 

 L. 0,05 to 0,065; B. 0,03 to 0,04 mm. Central nodule very small. Terminal fissures indistinct. 

 Axial area narrow, linear, unilateral. Central area indistinct. Strise 10 in 0,oi mm. parallel in the 

 middle, radiate at the ends. Puneta coarse, inequidistant, about 6 in 0,oi mm. At some distance 

 from the margin is a narrow, not punctate, space. — Quek. M. CI. II (2) p. 323 PI. XVIII f. 1. 



Marine: Oamaru, New Zealand, fossil! 



This is a very remarkable form, not closely akin to any known species. The median line 

 and the central nodule are especially peculiar. 



51. N. interlineata Grove and Sturt (1886). — V. elliptic-lanceolate. L. 0,i ; B. 0,05 mm. 

 Axial area narrow, very slightly dilated around the central nodule. Terminal fissures indistinct. 

 Strife 8 in 0,oi mm., radiate throughout. Puneta 8 in O.oi mm. forming irregularly undulating 

 rows. On' both sides of the median line is a narrow, arcuate, lateral area, inside which the puneta 

 form more regular longitudinal rows. ~ J. Quek. M. CI. II (2) p. 323 PL XVIII f. 2. 



Marine: Oamaru, New Zealand, fossil! 



A very remarkable species, which shews some resemblance to Diploneis nitida. 



52. N. fraudnlenta A. S. (1881). — V. elliptical with rounded ends. L. 0,03 to 0,045; 

 B. 0,019 to 0,023 mm. Axial area indistinct. Central area small, not sharply defined. Strise 14 

 (middle) to 18 (ends) in 0,oi mm. slightly radiate at the ends, composed of puneta, about 13 in 

 0,01 mm., disposed towards the median line in straight, somewhat distant, longitudinal rows. — 

 N. S. D. Ill p. 18 (without name). N. fraudulenta A. S. Atl. LXX f. 60. N. restituta A. S. 

 accord, to Grun. in CI. M. D. N:o 102 (1878). 



Marine: North Sea! Sebastopol! 



A small, very distinct species, not to be mistaken for any other. 



53. N. Novae Guineaensis Temp. (1891). — V. broad, biconstricted apiculate. L. 0,04 to 0,05; 

 B. 0,02 7 mm. Central nodule transversely dilated. Axial area narrow, linear. Central area trans- 

 versely dilated. Strise 11 in 0,oi mm., strongly radiate at the ends, composed of coarse puneta, 

 about 7 in 0,oi mm. forming undulating longitudinal rows. — Diatomiste I p. 71, PL XI f. 1. 



Brackish water: Yule- Island (New Guinea)! 



This is a very interesting form, not closely connected with any other. The median line 

 has somewhat arcuate components, which suggests that the valve is slightly genuflexed as in 

 Achnanthes. The coarse structure resembles that of Nav. Tuscula, but the direction of the termi- 

 nal rows of puneta is different and there is no appearance of a lineation across the puneta. The 

 dilated central nodule, as well as the strongly inclined strise, remind one of the lower valve of 

 Achnanthes danica and its allies, but the structure is much coarser and the valve strongly silicious. 



54. N. Pi Cl. (1893) — V. rhombic-lanceolate, with obtuse ends. L. 0,o8; B. 0,022 mm. Axial 

 area indi.stinct; central area small. Terminal fissures in the same direction. Strise 11 (middle) to 



