118 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS 



fMedi 



^1- 1 Median line approximate to the ventral margin A. Lagerheimii Cl. 



— distant from — — — A. cesttiarii Cl. 



16. P"f 



-i 



Frnstule almost orbicular A. Szaboi Pant. 



elongate-elliptical 17. 



j L. 0,02 to 0,036 mm A. Normani Rabh. 



\ L. 0,05 to 0,085 mm A. nom.mutata Gbun. 



Frnstule orbicular 19. 



— elongated 20. 



.,„ j L. 0,03 mm A. turgida 6reg. 



{: 



L. 0,045 to 0,08 mm A. costata W. Sm. 



■ Strise 7 to 9 in 0,oi mm 31. 



20. ■! — 9 to 13 — — 2S. 



— 13 to 20 — — 24. 



„.. j StrisB indistinctly punctate A. Terroris Ehb. 



i' 



\ — distinctly — A. Eimotia Cl. 



„„ J Zone with longitudinal rows of coarse puncta A. granulata Gebg. 



\ — transversely striate 23. 



„„ f L. 0,026 to 0,01 mm A. exigua Greg. 



I L. 0,04 to 0,12 mm A. macilenta Greg. 



n . ( Zone with faint divisions A. Normani Rabh. 



\ — — distinct — 25. 



n^ / Zone delicately striate A. coffwiformis åg. 



1. A. aestuarli Cl. (1894). — Frnstule elliptical, with broad, truncate ends. L. 0,o5; 

 B. 0,03 mm. Zone apparently smooth, with 4 to 5 broad divisions. Y. lunate, acnte, with 

 somewhat gibbous ventral margin. Median line arcuate in the middle of the valve. Axial area 

 broad, on the dorsal side frequently dilated around the central nodule. Dorsal side with 14 not 

 distinctly punctate, strise in 0,oi mm., not crossed by a longitudinal line. Ventral side broad, 

 with a median row of short strite, about 17 in 0,oi mm. — Diatomiste II p. 146 Pl. IX f. 10, 11. 



Brackish water (mouth of rivers): Africa, Cameroon! 



This species which resembles in the outline Ä. sulcata or Ä. truncata is remarkable for its 

 very broad, ventral side, in which characteristic it agrees with Cymhella. 



2. A. Lagerheimii Cl. (1894). — Frustule elliptical, with broad, truncate ends. L. 0,o5 

 to 0,0 7 mm. Zone with about 4 punctate (puncta 16 in 0,oi mm.) lines (divisions) in 0,oi mm. 

 Valve lunate, gradually tapering from the middle to the narrow ends. Dorsal margin arcuate; 

 ventral straight. Median line near the ventral margin. Axial area very large, apparently scabrous. 

 Dorsal side at the margin with a short stauros, reaching to the area, and marginal strise, 12 in 0,o i 

 mm. Ventral side smooth, except at the margin, where are short strite, 16 in 0,oi mm. (perhaps 

 belonging to the zone). — Diatomiste II p. 99 Pl. VII f. 2. 



Fresh water, moist rocks: Ecuador, Banos! 



This is a very curious species, remarkable for the short dorsal stauros. There is no nearly 

 akin form, as far as I know. Perhaps it is niost nearly related to A. veneta, through different 

 in most respects. 



3. A. veneta Kutz (1844). — Frustule elliptical with rounded truncate ends. L. 0,o2 to 

 0,ofi; B. 0,011 to 0,0 18 mm. Zone with several distinct divisions, about 12 in 0,oi mm., which 

 are more or less distinctly, transversely striate; strire 26 or more in 0,oi mm. V. with convex 

 dorsal and straiglit or slightly concave ventral margin. Ends subacute, not protracted or rostrate. 

 Central nodule strong, elongated. Median line straight close to the ventral margin; its central 

 pores distaiit. Dorsal side striate, ventral not. Dorsal strijc 20 in O.oi mm., more distant in the 

 middle, punctate. — Bac. p. 108 Pl. III f. 25. V. H. Syn. p. 58 Pl. I f . 17. A. fasciata Ehb. 

 1840 (according to H. L. Smith). A. Hohcnackeri Rauknii. Siiss. D. p. 31 Pl. IX f. 11 (1853). 

 A. quudricostata Rabh. Stissw. D. Pl IX f. 5 (1853). A. S. Atl. XXVI f. 74 to 80. A. tumidula 



