638 Proceedings of Royal Society of Edinburgh. [sess. 
rays 8, straight ; at middle of interradial spaces 2, somewhat faint 
subparallel lines radiating to the inner edges of the intervals ; the 
compartments reaching about J of radius inwards, the inner ends 
concave towards the centre on each side of, but somewhat pro- 
tuberant opposite, the rays, subhyaline or obscurely and minutely 
punctate, sometimes with a band of more prominent oblong mark- 
ings at their inner ends ; the intervals alternating gradually out- 
wards, their outer ends convex, and not reaching the border with a 
distinct oval, obliquely placed granule at one or both sides, those 
belonging to one interval sometimes meeting each other at the 
extremity of the interval. 
Habitat. — Barbados deposit (Greville). 
A. scutula. Grev., Trans. Micr. Soc. Lond., 1862, p. 52, pi. viii. 
fig. 47. — Diam. *04 mm. Central space regularly hexagonal, about 
*005 mm. broad, its sides convex, towards the centre hyaline. 
Markings : rays 6, straight ; the compartments reaching about § of 
radius inwards, their inner ends flat or somewhat concave, pro- 
tuberant at outer ends of rays ; a single large areola at their centro- 
lateral angles, tapering slightly outwards, its inner end convex but 
hardly protuberant, elsewhere the puncta obscure or unresolved; 
the intervals evident, expanding somewhat rapidly outwards, their 
outer ends rounded, reaching the border. Border narrow, hyaline. 
Habitat. — Barbados deposit (Johnson !). 
A. simulans. Grev., Trans. Micr. Soc. Lond., 1862, p. 52, pi. viii. 
fig. 36. — Circular or regularly and obtusely polygonal. Diam. 
•0375 to ’06 mm. Central space polygonal, *01 mm. broad, its 
sides convex towards the centre, hyaline. Markings : rays 9, 
straight ; at middle of interradial spaces somewhat broader, more 
faint lines radiating to the edges of the intervals ; the compart- 
ments reaching about i of radius inwards, their inner ends concave, 
concentric, with circumference sometimes slightly protuberant at 
ends of rays ; a distinct band of narrow radially elongate areolae 
fringing their inner ends, those at the centro-lateral angles most 
distinct and largest ; contiguous to the outer ends of the areolae 
a narrow, hyaline, indistinct band concave towards the border, 
beyond this the puncta obscure, about 5 in *01 mm., sometimes 
