74 P. T. CLUVE, SYNOPSIS OK THK NAVICUI.OII) 1)1 ATOMS. 



Var. rohusta Grun. (1878). — Broader, more clavate. — G. herc. v. rob. Gkun. Casp. Sea 

 Alg. p. 12 Pl. III f. 3. 



.Fre.sh water: Kamtscliatka (Grun.). 



Var. davnta Cl. — Broadest at tlie upper, rounded-truiicate end. L. U.ii; B. 0,u3 mm. 



Fresli water: Pitt River, Gol. (Grove Coll.)! 



Naviculse Luxuriosse Cl. 



Valve of elliptical outline, with depressed areas oii botli side.s of the median line, sepai'ated 

 by a more or less broad furrow from the marginal part. Axial and central area uniting in a 

 narrow space aroivnd the median line. Structnre: marginal, short strise and on the depressed areas 

 lai'ge distant puncta forming more or less regnlar longitudinal rows. 



Only a few forms of this section are known, and it seems at present impossible to deeide as 

 to their affinities. They have some resemblance to Biplotwif: nifescois. The short marginal stria^ 

 are apparently smooth, but in a specimen of -A^. luxuriosa from China I have seen in the marginal 

 fnrrow rows of distinct pnncta in continuation of the marginal strifE. 



1. N. luxuriosa Grev. (1862). — V. elliptic-lanceolate," with obtuse, sometimes cuneate, 

 ends. L. 0,o6 to 0, 09; B. 0,02» to 0,035 mm. Axial area narrow linear, slightly dilated in the 

 middle. Strite marginal, slightly radiate at the ends, 7 to 9 in 0, 01 mm. Fnrrow with rudi- 

 mentary, sometimes distinctly punctate, striai. Depressed lateral areas large with 3 to 5 longi- 

 tudinal rows of large puncta straight, or curved towards the median line. — Nav. luxuriosa Grev. 

 T. M. S. XI p. 18 Pl. I f. 10, 11. Nav. lux. var. cnneaia Brun. D. e.sp. n. p. 35 Pl. XVI f. 3. 



Marine: N. S. Wales (Grev.), China! Japan (Brun Coll.)! 



2. N. (lecoiva Grove and Sturt (1887). — V. elliptical, with obtuse ends. L. 0,o75 to0,i2r. ; 

 B. 0,03 to 0,04 5 mm. Median line straight; its terminal fissures turned in the same direction. 

 Axial area distinct, linear, slightly dilated around the nodnle. Marginal stria; 7 in 0, 01 mm., 

 apparently smooth, slightly radiate. Fnrrow crossed by faint stria;. Areas large, coarsely punctate; 

 puncta forming .5 to 6 irregularly undulating longitudinal rows, or somewhat scattered. — Grove 

 and Sturt Quek. M. Cl. III (2) p. 133 Pl. X f. 13. A. S. Atl. CLXXIV f. 27. 



Marine: Oamaru, New Zealand, fossil! 



3. N. trilinoata Grove and Sturt (1887). — V. elliptic-lanceolate. L. 0,i; B. 0,033 mm. 

 Axial area narrow, slightly dilated towards the middle. Stria; (i in 0, 01 mm. crossed by two longi- 

 tudinal blank bands, so that each half of the valve seems to bear three longitudinal rows of 

 elongate, coarse puncta. — Grove and Sturt Quek. M. Cl. III (2) p. 132 Pl. X f. 8. 



Marine: Oamaru, New Zealand, fossil! 



Naviculss Nicobaricse Cl. 



Valve elliptical in outline. Median line with approximate central pores and large comma- 

 like terminal fissures, bordered on both sides by a longitudinal row of large, sometimes confluent 

 puncta. Axial and central areas united in a lanceolate space. Strueture apparently smooth, distant 

 strife, radiate thronghout. 



This group comprises ouly two known species N. Nicoharica and N. Nij, of doubtful afHnity 

 to and other species. They have some resemblance to certain Diploneis forms, but the central and 

 terminal nodules are very diiferent. They seem to me provisionally to Le nearest akin to T)ijiJo)t. 

 Jiiociihifd and N. forriputa, althongh the relation is a distant one. 



