116 
GrevillE;, on Asterolampra. 
A very singular species, having the ordinary umbilical 
lines furnished with an angular bend in the middle, while 
the median lines are straight. It thus forms a transition 
from the previous species of the section to the following one. 
10. Asterolampra Darwinii. — Areolated segments some- 
what square at the base; umbilical lines with an angular 
bend ; median lines cuneate, with an angle midway, furnished 
with a minute spine-like projection. Diameter "0019" to 
•0035". (PI. IV, figs. 12, 13.) 
Asteromplialus Darwiuii, Elir., Bed. Monat«b., 1844, p. 200, (June), 
fig. 1 ; Kiitz., 1. c, p. 129 ; Pritch., 1. c, p. 320 ; Mic. Diet., p. 71 
(5 rays). 
Asterompbalus llossii, Ehr., Berl. Moiiatsb., 1844, p. 200, pi. (June), 
fig. 2; Kiitz., 1. c, p. 130; Pritcli., 1. c, p. 321; Mic. Diet., 
p. 71 ; Elir., Microgeol., pi. 35, A. xxi, fig. 4 (6 rays). 
Hab. — Antarctic Ocean, Dr. J. D. Hooker. Monterey 
stone, Professor Walker- Arnott. 
The determination of this species has been accompanied 
with a good deal of perplexity. The figures given by Ehren- 
berg represent the base of all the areolated segments as 
curved — not in the remotest degree as tending to square ; 
whereas in the specimens obtained by Professor Walker- 
Arnott from the Monterey stone (all of them four-rayed) , the 
hyaline area is decidedly quadrangular. Nay, more than 
that, the outline of the hyaline area between the median and 
adjoining rays is slightly but unequivocally convex instead of 
concave. It is difficult to conceive how so great an amount 
of error should have crept into Ehrenberg^s figures, if tiie 
Monterey specimens be really the same. I confess that I 
am not quite satisfied on this point, although the umbilical 
and median lines agree. In deference, however, to Professor 
Walker-Arnott^s opinion, I refer his Monterey valves in the 
mean time to this place, and ofier representations of two 
examples, in order that the discrepancy between them and 
Ehrenberg^s figures may be better understood. It will be 
noticed that there is some difference in the median lines in 
the two valves ; but the absence of the angles in figure 13 
may be regarded as accidental. 
Section III. — Eays unequal. Umbilical lines radiating 
from the top and sides of the median lines ; which latter pass 
beyond and enclose the central point. — Spatangidium. 
* Umbilical liueb witiiouL an angular bend. 
11. Asterolampra flabellata. — Areolated segments curved 
