342 Transactions of the Society. 



centre, rarely hyaline. Central space rounded or 3-4-anglecl, about 

 1/21 of diam. broad, punctate. Markings rounded or angular, 3 to 

 3^ in 0*01 mm.; interspaces most obvious towards centre, narrow, 

 irregular, and punctate ; rows moniliform towards border, rarely 

 Bubfasciculate, secondary rows irregular, oblique, or subconcentric 

 towards centre. Primary rays distinct, between the rows a narrow 

 wavy space. Border stria? 10 in 0*01 mm., 1/28 to 1/55 of radius 

 broad. Processes 3 to 5, insertion 1/4 to 1/11 of radius from cir- 

 cumference, large but faint, proximal portion smaller than distal, free 

 ends flattened, angles rounded, inner end of axial structure distinct, 

 obovate, space at base distinct, punctate. — PL VII. fig. 7 ; Sch. AtL, 

 pi. xxxvi. tig. 11 ; pi. civ. fig. 5. A. Habirshawii Pant., Fossil. Bacil. 

 Ung., p. 58, pi. xxix. fig. 296; A. Miilleri Grun., Sch. AtL, pi. xli. fig. 11. 



The inner layer of the valve is sometimes minutely apiculate. On 

 corresponding side of base of each process there occurs a faint oval 

 mark, only visible when the valve is transparent, as in A. Broivneii 

 and A. harbaclensis. The scar of the broken-off process is roundly 

 elliptical. Schmidt distinguishes A. Miilleri by its being quite flat, 

 but this seems scarcely sufficient to found another species. 



Habitat : Peruvian guano (Kae ! Hardman ! Macrae ! Weissflog !) ; 

 Bolivian guano (Kinker!); Pabillan de Pico guano (Kinker! Cleve !); 

 Ichaboe guano ( O'Meara !) ; " guano " (Norman ! Macrae !) ; San 

 Filipe guano (Kalfs). 



Var. irregularis. — Diam. 0*1075 mm., a faint depression opposite 

 each process. Surface flat at centre. Colour pale lurid grey, border 

 darker. Markings in zones, from centre to semi-radius rounded, at 

 semi- radius on a band 1/7 to 1/8 of radius broad, angular, from this 

 to processes rounded, between processes on a narrower band 1/21 to 

 1/24 of radius broad, and separated from inner and outer portions by 

 granulate narrow areas, again angular. Primary rays with markings 

 in rows similar to those on corresponding areas of compartments. 

 Border striae 7 to 8 in 0'01 mm., 1/23 to 1/24 of radius broad. 

 Processes 3, insertion about 2/11 of radius from circumference. — 

 PL VI. fig. 5. 



Habitat : Pabillan de Pico guano (Weissflog !). 



A. hyalimis Pant., Fossil. Bacil. Ung., p. 58, pi. i. fig. 5. — Diam. 

 ' 25 mm. Surface, central portion flat to processes with outer edge 

 indistinct and concave between these, slope to border gentle. Colour 

 light grey, darker towards border. Central space quadrate, about 

 1/25 of diam. broad, delicately punctate. Markings round, small, 

 outlines faint, central dot distinct, interspaces unequal, large, punc- 

 tate ; sub-equal to zone of processes, near border moniliform ; rows 

 straight radial, secondary rows irregular, oblique towards centre, 

 straight between processes. Primary rays undifferentiated towards 

 centre. Border stria? faint, 8 to 10 in 0*01 mm., inner edge definite, 

 about 1/50 of radius broad. Processes 9, insertion about 1/8 to 1/10 

 of radius from circumference, clear space at base non-punctate, almost 

 semicircular, with the greater convexity towards the centre. 



