8^ p. T. OLRVK, synopsis of THR NAVIOULOID DIATOMS. 



„ . I Valve without ocelli . . . . . .... 75. 



\ — with — . . . . ... ... .... 76. 



_. I Furrows narrow .... . . . D. dalmatica Geun. ' 



' ■ \ — broad .... . . . D. Vesjaa Cl. 



„„ j Ocelli in a marginal band D. Crahro Ehb. 



\ — rows alternating with the costie 77. 



„_ J Furrows broad . . . D. gemmatula Gktjn. 



\ — narrow . . . . . ... 78. 



f Costse 3 to 4 in 0,oi mm. . . . . D. vagabunda Eeun. 



78. < — 5 to G — . D. lesinensis Gbtjn. 



I — 7 — . . . . D. prisca A. S. 



D. Hudsonis G-run. (1892). — V. hyaline, elliptical, with more or le.ss rounded ends. L. 

 0,036 to 0,05; B. 0,012 to 0,02 mm. Central nodule quadrate, its horns slightly divergent in the 

 middle. Furrows forming a small, rhomboid, not striate, space around the central nodule. Parts 

 outside the furrows striate. Strise fine, 24 to 25 in 0,oi mm. slightly radiate at the ends, finely 

 punctate; puncta forming obliquely decussating rows. — Nnricula {Diploneis?) Hudsonis (Grun.) 

 Cl. in Diatomiste I p. 77 PL XII f. 8. 



Brackish water: Hudson River! 



This little form is very remarkable and not closely connected with any other known species- 

 It seems to be most nearly related to D. hyalina, but there are considerable differences. 



1. D.? bioculata G-rvn. (1881). — V. elliptical, with rounded ends. L. 0,o2 to O.ose; B. 

 0,013 to 0,015 mm. Central nodule elongated; its horns close to the median line. Central pores 

 distant, incrassate. Furrows broader than half of the breadth of the valve. Strise 17 to 22 in 

 0,01 mm. not distinctly punctate, continued across the furrows to the mediail line, slightly radiate 

 throughout. — Nav. Uoculata Grun. A. S. Atl. LXX f. 9, 10, 11, VII f. 49? 



Marine: Balearic Islands! Adriatic! Java! Port Jackson! Galapagos Islands! 



Yar. vittata Cl. — L. 0,04; B. 0,oi5 mm. Central nodule very narrow; central pores distant. 

 Furrow separated from the exterior part of the valve by a linear, broad band. Strife 17 in (),oi 

 mm., on the furrows punctate. — PI. I f. 15. 



Marine: Ceylon! 



The exact place of this species is difiicult to decide. The incrassated central pores recall 

 those of Nav. forcipata, but nevertheless I believe it to be a Diploneis, akin to D. hyalina. 



2. D. inscripta Cl. N. Sp. — V. lanceolate, subacute, convex. L. 0,o65; B. 0,oi7 mm. 

 Central nodule small; its horns close to the median line. Central pores approximate, incrassate. 

 Furrows as broad as half of the valve. Strise 10 in 0,oi mm. continued across the furrows, not 

 distinctly punctate, parallel, very slightly radiate in the ends. — PI. I f. 17. 



Marine: Gulf of Naples! China! 



This species seems to connect the genus Cymatoneis, to which it has some resemblance, with 

 the forms of the group of D. nitescens. 



3. D. hyalina Done. (1861). — V. hyaline, thin, elliptical. L. 0,04 5 to 0,o7 6; B. 0,oi4 to 

 0,026 mm. Central nodule somewhat elongated; its horns slightly divergent in the middle. Furrows 

 much broader than half of the breadth of the valve. Strise 22 in 0,oi mm., distinct outside, fainter 

 in the furrows, fading away towards the horns of the median line. — Nav. hyalina Donk. M. J I 

 p. 10 PI. I f. 6. B. D. p. 5 PL I f. 1. A. S. Atl. LXX f. 1—5. 



Marine: Finmark! North Sea! 



' Yar. of D. Crahro. 



