20 



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



Artificial key. 



J Valve more or less boat-shaped 



\ — — — reniform 



f StrisB 10 to 11 in 0,01 mm 



\ — 20 to 23 - .... 



{Zone with a few larger stigmas .... 

 — without stigmas 



{Keel strongly inflected in the middle . . 

 — not, or slightly, inflected 



j Striae 15 to 16 in 0,oi mm 



\ Striae very fine 



( Strise transverse .... 



\ — curved, divergent towards the median line 



I Striae coarse (8 in 0,01 mm.) 



\ — finer (20 in 0,oi mm.) 



! Valve large (L. 0,17 mm.) . . . 



— small (L. 0,02 to 0,03 mm.) . . 



. 2. 

 . ... 4. 

 A. coarctata Br. 



... 3. 



A. pulchra Gee v. 



A. decipiens Gkun. 



5. 



..... 6. 

 A. intermedia Lewis. 

 A. insecta Geun. 

 ... .8. 



7. 



A. Amphitritis Castr. 

 A. complexa Greg. 

 . A. javanica Cl. 

 A. minuta Cl. 



1. A.(?; coarctata Brun (1889). — V. lanceolate, acute. L. 0,ii5 to 0,135; B. 0,02; Height 

 0,025, at the constriction 0,oi3 mm. Median line highly elevated between the central nodule and 

 the ends. Central area small, unilateral. Junction-line between the keel and the lower part of 

 the valve very distinct, with a sinus on each side of the central nodule. Striae 10 to 11 in 0,oi 

 mm., convergent on both sides of the central nodule, punctate, puncta 12 to 13 in 0,oi mm. — 

 Amphiprora coarct. Brun. D. foss. du Japon p. 14 PL III f. 12.' 



Marine: Japan, fossil and living (Brun)! 



As the entire frustule is not known, it^ is impossible to decide whether this species, which 

 has a great resemblance to a true Amphiprora, belongs to Auricula or to the sections Plagiotropis 

 or Amphitropis of Tropidoneis. The incompletely described Amphiprora nitida GtEEV. (Edinb. 

 N. Ph. J. XVIIl p. 40 f. 18, 1856) has some resemblance to A. coarctata, but has not a com- 

 plex zone. 



2. A. decipiens G-run. (1882). — Erustule quadrate to rectangular, slightly constricted in 

 the middle. L. 0,0 6 to 0,ii; B. 0,05 mm. Junction-line distinct, sinuose. Central area indistinct. 

 Strise 20 in 0,oi mm., a little closer on the valve. Connecting zone, on the dorsal side, with broad 

 divisions, about 3 in 0,ooi mm., transversely striate; striae 22 in 0,oi mm. Divisions narrow on 

 the ventral side. — Amphoropsis decipiens Grun. in Cl. M. D. N:o 309. V. H. Syn. PI. XXII bis 

 f. 11. Amphiprora plicata Greg. D. of Clyde p. 505 PI. XII f. 57 (1857)? 



Marine, sestuaries: Scotland! 



3. A. pulchra G-rev. (1863). — Frustule membranaceous, quadrate, slightly constricted. 

 L. 0,075; B. 0,04 5 mm. Connecting zone with numerous divisions, about 5 in 0, 01 mm., transversely 

 striate; striae about 22 in 0,oi mm. On the zone, close to the valve, are 3 or 4 large isolated 

 stigmas. Valve with transversely dilated central nodule and elevated keel, bordered with a row 

 of puncta, 6 in 0,oi mm. Striae 22 in 0,oi mm. ^ Amphora pulchra Gbmy. Edinb. N. Ph. J. XVIII 

 p. 184 f. 2. — Auricula pule. PL II f. 23. 



Marine: Queensland (G-rev.)! China! Macassar Straits (Grove coll.)! South Pacific Ocean (Van 

 Beurcks coll.)! 



The following incompletely described forms seem allied to this species: Amphiprora lineata 

 G-REV. (Edinb. N. Ph. J. XVIII p. 40 f. 19; 1863) and Amph. Jolisiana Grev. (1. c. p. 186 f. 11). 



4. A. insecta Grun. (1876). — Frustule membranaceous, globose. L. 0,o6 to 0,ii; B. 0,o4 

 to 0,0 5 mm. Median line strongly inflected towards the centre of the frMptule. Central nodule 



