376 Transactions of the Society. 



weed (Norman !) ; west coast South America (Kinker !) ; Ilouanillas 

 (Kinker!). 



Var. Johnsonii. A. Johnsonii Arnott, in Pritch. Inf., p. 844. 

 — Diam. 0*05 to 0'125. Surface fiat to processes. Colour light 

 grey to transparent. Central space round or angular, 1/20 to 1/25 

 of diam. broad. Markings polygonal, 4 in 0*01 mm. Outlines 

 more delicate, secondary rows less distinct. Border stria3 6 to 10 in 

 0*01 mm., 1/20 to 1/25 of radius broad. Processes 4, insertion 1/4 

 to 1/5 of radius from circumference, proximal portion semicircular, 

 distal clavate ; at Jbase a delicate, rounded, obliquely placed lobe on 

 corresponding side of all the processes ; the crescentic line distinctly 

 angular. 



Habitat : S. African guano (Greville !) ; Nankoori deposit (Gray !) ; 

 Cambridge deposit, Barbadoes, Algoa Bay, and Sumatra (Hardman !) ; 

 Nicobar (Weissfiog!) ; Sierra Leone (Leuduger-Fortmorel, Cleve!). 



Var. africana. A. africanus Cottam, Journ. Quek. Mic. CI., 

 1876, p. 149, pi. xii. figs. 1, 2, 3, 8.— Diam. 0-0625 to 0-1125 mm. 

 Surface rising slightly to processes. Central rosette 1/12 to 1/15 of 

 diam. broad. Markings with still fainter outlines, 4 to 5 in ' 01 mm. 

 Border about 1/45 of radius broad. Processes 4 or 5, rarely 2, 3, 6, 

 or 0; insertion 1/4 to 1/6 of radius from circumference, proximal 

 portion flask-shaped, with a small cylindrical portion at outer end 

 whence a long delicate mark proceeds inwards, external crescentic 

 line forming a uniform arc ; in girdle aspect curving outwards, and 

 concave on outer side, sigmoid towards centre. Girdle ■ 0225 mm. 

 wide, in frustule 0*079 mm. in diam., with four faint parallel 

 lines. — A. Johnsonii Arnott, Sch. Atl., pi. xxxvi. figs. 1, 2 ; pi. xli. 

 figs. 7-10 ; pi. civ. fig. 1. Hauck & Eichter, Phykothek. Univ., 

 1887, No. 150. 



Habitat : Banana Creek, Congo Kiver, W. Coast Africa (Cottam ! 

 Macrae ! &c.) ; Nukahiva sand, Marquesas (Kitton ! Weissfiog ! 

 Cleve). 



(/3) Processes large. 



A. Battrayii Grove & Sturt, Journ. Quek. Mic. CI., 1887, p. 139, 

 pi. xi. fig. 29. — Diam. ■ 075 to ■ 235 mm. Surface almost flat for 

 1/2 to 5/7 of radius, its outer edge angular just within processes, 

 convex between these; slope to border steep. Colour pale lurid to 

 pale grey, darker between processes. Central space 3-4-angled, 1/30 

 to 1/47 of diam. broad, hyaline. Markings 4 in 0'01 mm., outlines 

 distinct, subpearly, rows straight radial, at sides of processes areolae 

 oblique. Primary rays distinct, rows in contact or diverging slightly 

 at outer ends. Border stria? punctate, 10 to 12 in • 01 mm., secondary 

 oblique rows distinct, 1/13 to 1/15 of radius broad. Processes 2 to 4, 

 insertion 2/5 to 2/9 of radius from circumference, proximal portion 

 evanescent, distal knob-like, constriction well marked, free ends 

 rounded, clear space at base distinct, length 1^ to 3 times breadth. 

 In girdle aspect height of centre ■ 0225 mm., processes truncate. — 



