340 Transactions of the Society. 



A. Beeveriiv Johnson, in Pritch. Inf., p. 844, pi. vi. fig. 5. — Diam. 

 • 0(325 to ' 08 mm. Surface flat to zone of processes. Colour steel 

 grey at centre, smoky grey towards border. Central space irregularly 

 rounded, 1/16 to 1/17 of diam. broad, closely punctate. Markings 

 round or bluntly angular, 4 in "01 mm., central dot dark, interspaces 

 irregular, small, punctate. Primary rays with markings round or 

 compressed when in contact, the space between the rows evident, ex- 

 panding gently outwards. Border striae 8 to 10 in 0*01 mm., 1/25 

 to 1/32 of radius broad, mostly in contact with outer ends of rows of 

 markings. Processes 3, insertion about 1 /5 of radius from circumfer- 

 ence, no space at base. — Sch. Atl., pi. xxxvi. fig. 12 ; Cleve, Diats. 

 Vega Exp., p. 509. 



Johnson's type in Greville's collection is somewhat imperfect, the 

 processes being broken oft', leaving a roundly elliptical scar. 



Habitat : New Zealand (Johnson !) ; Sydney (Cleve). 



Var. ceylanica. A. Comberi var. ceylanica Grun., Cleve & Moller's 

 Diat., No. 278. — Diam. 0"06 mm. Central space less distinctly 

 punctate. Markings smaller, 6 in * 01 mm. Primary rays less 

 obvious, the rows diverging less towards processes. 



Habitat : Ceylon (Grove !). 



A. simplex sp. n. — Sp. aff. A. decoro Grev., Sch. Atl., pi. xxxiii. 

 fig. 9. — Diam. 0*1275 mm. Surface flat for 1/3 to 1/2 of radius. 

 Colour pale grey at centre, light bluish on median zone, pale grey 

 towards border. Central space obtusely angular, about 1/3 of diam. 

 broad, hyaline, boundary faint. Markings rounded granules, 4 to 5 in 

 0*01 mm., with narrow, clear interspaces, arranged in secondary 

 irregular concentric bands, and less crowded towards central space. 

 Primary rays inconspicuous, rows diverging but slightly outwards, 

 interspace hyaline. Border striae 10 in - 01 mm., 1/31 to 1/32 of 

 radius broad, separated from radial rows by an irregular clear space 

 about 1/53 of radius broad. Processes 6, symmetrical, insertion 

 about 1/5 of radius from circumference, proximal portion rounded, 

 distal more cylindrical, constriction median, sharp but shallow, free 

 ends rounded, length about 31 times breadth, clear space at base 

 small. 



More nearly allied to A. probabilis and A. Comberi than to 

 A. decorus. Scar of broken-ofF process is obovate. 



Habitat : Monterey (Weissflog !). 



A. prdbcMUs Sch., Atl., pi. xxxvi. figs. 13, 14, escl. 15, 16. — Diam. 

 from ' 045 to ■ 105 mm. Surface flat to about half-way to processes, 

 within the border almost flat for about 1/10 of radius. Colour pale 

 grey, darker towards processes, sometimes light blue at centre. Central 

 space circular, elliptical, or irregular, 1/16 to 1/21 of diam. broad, 

 finely punctate, a limiting band of markings rarely distinct. Markings 

 rounded near centre, 4 in 0"01 mm., moniliform near border, central 

 dot minute; interspaces on inner half narrow, irregular, punctate; the 

 rows sometimes deflected near processes, only distinct beyond middle 

 of radius. Primary rays distinct only near processes. Border striae 



