20 



Artificial key. 



j Valve more or less bo<at-sliai)ecl 2. 



\ — — — • reniform 4. 



StrisB 10 to 11 in 0,01 mm , . . . A. coarctata Bh. 



I 



( Stria 



\ — 20 to 22 - 3. 



is 



Zone with a few larger stigmas A. jmlchra Grev. 



without stigmas A. decipiens Grun. 



Keel strongly inflected in the middle 5. 



— not, or slightly, inflected (>. 



Striae 15 to 16 in 0,oi mm A. intermedia Lewis. 



Striae very fine .-1. insecta Grun. 



I Striae transverse H. 



\ — curved, divergent towards the median line 7. 



j Strise coarse (8 in 0,oi mm.) A. Amjyhitritis Castr. 



^ — finer (20 in 0,0 1 mm.) . . • A. complcxa Greg. 



) Valve large (L. 0,17 mm.) A. javanica Cl. 



\ — small (L. 0,02 to 0,03 mm.) A. niinuta Cl. 



1. A.(?) cojirctata 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. Strife 10 to 11 in 0,oi 

 mm., convergent on both sides of the central nodule, punctate, puncta 12 to 13 in 0,01 mm. — 

 Amphiprora coarct. Brun. D. foss. du Japon p. 14 PI. Ill 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 Grev. (Edinb. 

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

 plex zone. 



2. A. decipiens (tRUN. (1882). — Fru.stule quadrate to rectangular, slightly constricted in 

 the middle. L. (),o6 to 0, 11; 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 0,001 mm., transversely striate; strifB 22 in 0,oi mm. Divisions narrow on 

 the ventral side. — Amplioropsis decijnem GrRUN. in CI. M. D. N:o 309. V. H. Syn. PL XXII bis 

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



Marine, Pestiiaries: Scotland! 



3. A. piilc'Iira Grev. (18fi3). — Frustule membranaceous, quadrate, slightly constricted. 

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

 striate; striai 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, (3 in 0,o 1 mm. Striai 22 in 0,oi mm. — Amphora 2Julchra Grev . Edinb. N. Ph. J. XVIII 

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



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

 Heurcks coll.)! 



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

 Grev. (Edinb. N. Pli. J. XVIII "p. 40 f. 19; 18(53) and Amph. Jolisiaiia Grev. (1. c. p. 18(1 f 11). 



4. A. iusecta Grun. (1876). — Frustule membranaceous, globo.se. L. 0,o6 to 0,ii; B. 0,o4 

 to 0,05 mm. Median line strongly inflected towards the centre of the fntstule. Central nodule 



