V 
GiiEviLLE, on Asterolampra. 117 
at the base ; umbilical lines all straight^ radiating from tlie 
apex and sides of the median lines. Diameter -0017" to 
•0024". 
Spatano-idium flabellatum, De Breb., Bull. Soc. Limi. de Kormand., 
vol. iii, PI. 3, fi- 3. 
Asteromplialus flabellatus, Grev., Mic. Journ., vol. vii, p. 160, PI. 7, 
figs. 4, 5. 
Spatangidium peltatuni, De Breb., 1. c, PI. 3, fig. 4. 
Hab. — Peruvian Guano^ De Brebisson. Californian Guano. 
Aiier a reconsideration of the claims for distinction put 
forth on behalf of the two diatoms above quoted^ I cannot 
find any really trustworthy characters to separate them. The 
slightly arcuate rays in S. flabellatmn will not alone suffice^ as 
this appearance may be seen occasionally in species whose 
rays are normally straight ; and the " subpinnate disposition 
of the rays in S. peltatum is rather a deception^ arising 
simply from the number being uneven^ and the odd ray 
being placed on the apex^ in the direction of the median lines. 
Beyond these two characters — the one as uncertain as the 
other — there is nothing to rest upon. The number of rays in 
the specimens I have seen is ten or eleven ; but a larger 
series of examples would probably show a wider range. The 
areolation is very minute. 
12. Asterolampra Hiltoniana, n. sp. Grev. — Areolated seg- 
ments acutely curved at the base ; umbilical lines radiating 
from the apex and sides of the median lines^ the two lower 
pair suddenly defiexed. Diameter -0038" to -0052". (PL IV, 
fig. 15.) 
Hab. — Algoa Bay Guano, R.K.G. Indian Ocean soundings, 
made by Captain Pullen. 
On a former occasion, this species was referred to by me as 
probably distinct but at that time I had only seen two 
examples with ten rays each. In the Indian soundings I 
have met with numerous individuals (including fractured ones, 
which are often equally instructive), and my previous im- 
pression is fully confirmed. The latter specimens are much 
finer, the rays varying from fifteen to nineteen. Three of 
the umbilical lines on each side are generally defiexed, but 
the lowest two on each side are more or less suddenly bent 
downwards in the middle, either by a sharp curve or angle. 
In the African specimens the lines are all simple. So are 
they all in an Indian valve of eighteen rays. In the Indian 
one, however, which 1 have figured, with nineteen rays, three 
of the lines are forked. It is a ^'ery transparent species, and 
* 'Mic. Journ.,' vol. vii, p. ICO. 
