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



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



^ \ — — distant from — — — A. CEstuarii Cl. 



.. , I Friistule almost orbicular A. Szahoi Pant. 



I — elongate-elliptical 17. 



..- ) L. 0,02 to 0,03.5 mm A. Normani Rabh. 



\ L. 0,05 to 0,085 mm '. . . . A. comnmtafa Grun. 



Frustule orbirular 19. 



elongated 20. 



..„ ^ ^. 0,03 mm A. tnrgida Greg. 



18. I™ 



( L. 0,03 

 \ L. 0,04J 



15 to 0,08 ram A. costafa W. Sm. 



f Striae 7 to 9 in 0,oi mm 21. 



20. ] — 9 to 13 — — 22. 



I — 13 to 20 — — 24. 



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



I — distinctly — ^1. Eunotia Cl. 



g„ ) Zone with longitudinal rows of coarse puncta A. granulata Greg. 



^ \ — transversely striate 23. 



9.. I Ij- 0,025 to 0,04 mm A. exigua Greg. 



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



„ . ) Zone with faint divisions A. Normani Rabh. 



„. I Zone delicately striate A. coffwiformis Ag. 



' \ — distinctly — A. acutiuscula Kutz. 



1. A. jestnarii Cl. (1894). — Frustule elliptical, with bi-oad, truncate ends. L. 0,05; 

 B. 0,03 mm. Zone apparently smooth, with 4 to 5 broad divisions. V. lunate, acute, 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, strife in 0,oi mm., not crossed by a longitudinal line. Ventral side broad, 

 with a median row of short stripe, 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 A. sulcata or A. truncata is remarkable for its 

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



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

 to 0,07 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 striae, 12 in 0,oi 

 mm. Ventral side smooth, except at the margin, where are short strict, 16 in 0,01 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. Perhajis it is most nearly related to A. veneta, through different 

 in most respects. 



3. A. veiieta KtiTz (1844). — Frustule elliptical with rounded truncate ends. L. O.02 to 

 0,0*;; B. O.du to 0,oi8 mm. Zone with several distinct divisions, about 12 in (>,oi mm., which 

 are more or less distinctly, transversely striate; stri;c 2() or more in 0,01 mm. V. with convex 

 dorsal and straight 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 distant. Dorsal side striate, ventral not. Dorsal striii?- 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. Hohenackeri Rabenh. Suss. D. ]). 31 PL IX f. 11 (1853). 

 A. quadricostata Rabh. SIlssw. D. PI IX f. 5 (1853). A. S. Atl. XXVI f. 74 to 80. A. tuniidula 



