632 
Proceedings of Royal Society of Edinburgh. [sess. 
subregular intervals, and narrow costate ridges towards the outer 
ends of these rays. Border with delicate striae, 16 to 18 in '01 mm. 
— Walker and Chase, New and Rare Diat ., ii. p. 2, pi. v. fig. 10. 
Habitat. — Springfield deposit, Barbados (Hardman !); “Barbados” 
(Johnson! Greville !); Cambridge deposit, Barbados (O’Meara!). 
Artificial Key. 
/'Primary rays obvious outside of circlet of large 
1 I areolse, narrow prominent costse at their outer 
M ends, .......... Johnsonii. 
l^No such costse, 2. 
Central space subcircular, surrounded by a band 
of large markings. Markings within the circlet 
of large areolse in uniform, curved, decussating 
rows, beyond the circlet decreasing gradually 
outwards. Apiculi faint, coronata. 
Central space obtusely triangular, without a dis- 
2 I dinct limiting band of markings. Markings sub- 
‘ ' circular towards central space. Apiculi minute, 
but more evident, ...... excellens. 
Central space minute, indistinct. Markings 
within the circlet of large areolse rounded, in 
obscure curved radial rows, beyond the circlet 
the rows moniliform. Non-apiculate, . . . sylendida. 
LNo central space, ....... 3. 
(An inconspicuous rosette. Markings outside 
circlet of large areolse increasing gradually in 
breadth towards border, ..... elabomta. 
3. No rosette. Markings within the circlet of large 
areolse in substraight decussating rows without 
order, beyond the circlet subequal or slightly 
l smaller near border, hyberborect. 
STELLADICUS, gen. n. 
Circular. Central space and rosette absent. Markings : rays 
clavate, their inner ends rounded, meeting at centre, attenuating 
towards border, at middle of the interradial areas similar, but narrow 
faint rays extending to middle of inner ends of compartments, and 
continued thence as straight narrow lines to the border; the com- 
partments each consisting of three subequal parts separated by 
narrow straight lines reaching the border, the inner end of each part 
convex towards the centre; areolate, the areolse forming oblique, 
straight, decussating rows. Border narrow, hyaline. — Asterolampra , 
pro jparte Norman, Trans. Micr. Soc. Lond ., 1861, p. 6. 
S. stella , Battray. Asterolampra stella. Norman, Trans. Micr . 
Soc. Lond., 1861, p. 6, pi. ii. fig. 1. — Diam. ’09 mm. Markings: 
