654 Proceedings of Royal Society of Edinburgh. [sess. 
("Central areolate area inconspicuous — represented by 
two areolse ; rays sometimes dichotomous ; com- 
I partments with inner ends curved or flattened on 
24 J opposite sides of rays, the areolae obscure or unre- 
' | solved, Grevillei. 
Central areolate area sometimes large ; compartments 
I with inner ends concave to truncate, areolae 
l obvious, affinis. 
i 
ASTEROMPHALUS. 
Ehrb. Emend., Mon. Bex. Ah., 1844, p. 198. — Circular, more 
rarely flabelliform, oval, or suboblong. Colour pale grey or sub- 
hyaline, inconspicuous. A centro-lateral area distinct, extending 
to or slightly beyond the middle of the clear area, rarely quite 
across the latter — ovate, clavate, or with sides somewhat deeply 
constricted. Markings : rays distinct, simple or dichotomous, 
extending from the apex or also from the sides of the centro- 
lateral area, straight, arcuate, flexuous or sharply bigeniculate, 
sometimes with short lateral rami passing obliquely outwards from 
the geniculations; interradial spaces hyaline, or with a subdistinct 
median area, continuous with the intervals between the compart- 
ments; the compartments equal or unequal, their inner ends 
convex, obliquely to transversely truncate or concave ; areolae 
distinct or inconspicuous, the outermost row most manifest ; 
intervals between the compartments tapering slightly outwards, or 
of uniform width, their outer ends rarely expanded, sometimes not 
reaching border; a subobsolete interval distinct, straight, rarely 
distinctly arcuate; sometimes an obscure granule (apiculus?) at 
outer ends of intervals. Border narrow, hyaline. — Spatangidium, 
de Breb., Bull. Soc. Linn. Normand ., 1857, p. 296 ; Asterolampra , 
Grey ., pro parte, Trans. Micr. Soc. Bond., 1860, p. 102; Mesasterias, 
Ehrb., Abli. Ber. Ah., 1872, p. 392; Actinogramma , Ehrb., Abh. 
Bex. Ah., 1872, p. 254. 
§ 1. Obscuri. 
The outer ends of the rays penetrating a short distance into the 
apices of the compartments ; the intercompartmental intervals pro- 
longed as definitely marked areas to the centre. 
Astreom. centraster. Johnston, Quart. Jour. Micr. Sci 1860, 
p. 12, pi. i. fig. 10. — Diam. about *072 mm. Colour of compart- 
