650 Proceedings of Royal Society of Edinburgh. [ sess . 
\ to -J- of radius inwards, their inner ends slightly angular towards 
centre or transversely truncate, the areolae decreasing but slightly 
towards the border, the outermost row more conspicuous; the 
intervals of equal breadth throughout, their outer ends reaching 
the border. Border narrow, hyaline. 
Habitat. — Barbados deposit (Johnson ! Deby !) ; Oamaru deposit 
(Grove !) ; Newcastle estate, Barbados (Grove !). 
A. decora. Grev., Trans. Micr. Soc. Lond., 1862, p. 45, pi. vii. 
figs. 4-6. — Diam. *04 to *1375 mm. Central space subtriangular 
or absent, central areolate area distinct, up to *02 mm. broad. 
Markings on the central area unequal, 2 to 3 in *01 mm., those 
around its edges largest; rays 5 to 19, straight, sometimes meeting 
at the centre ; the compartments reaching about £ of radius inwards, 
their inner ends slightly concave or convex towards the centre, the 
areolse at their inner ends largest, 4 in *01 mm., the others decreas- 
ing rapidly outwards from 6 to 10 in *01 mm.; the intervals of 
uniform breadth, reaching close to the border. — A. decora , var. 
Cstr., Diat. Chall. Exjped ., 1886, p. 136, pi. xvi. fig. 9. 
In the variation in size of the areolate central area this species 
approaches the forms of A. vulgaris and A. rylandsiana. The size 
of the markings on the compartments is less, according as the 
specimens decrease in size. 
Habitat. — Cambridge deposit, Barbados (Greville ! Hardman !); 
“ Barbados ” deposit (Greville !) ; Springfield deposit, Barbados 
(Hardman !); Oamaru deposit (Deby ! Grove ! Hardman !). 
Yar. concentrica , nov. — Diam. *095 to *125 mm. Central 
areolate area from *0375 to *065 mm. broad, a rosette some- 
times evident. Markings on central area 1-J to 2 in *01 mm., 
with central dots large, and in evident concentric, less evident 
radial rows ; rays many ; at middle of interradial space a distinct 
hyaline area, with inner end close to border of central area; the 
compartments reaching from ^ to of radius, areolse obvious, 4 to 
8 in *01 mm.; the intervals gradually increasing in breadth out- 
wards, their outer ends transversely truncate. 
Habitat. — Oamaru deposit (Grove ! Hardman ! Deby !); Cam- 
bridge deposit, Barbados (Johnson !). 
