Mr. H. J. Carter on Holasterella and Hemiasterella. 149 
more or less retained till it equals in size the full-grown “ ball ” 
itself; and thus its ontogenetic origin is determined. 
A similar transition of the flesh-spicule is, according to 
Schmidt, met with in his Vioa Johnstonii , where in one in¬ 
stance the spiculation consists of an acerate skeleton with 
stelliform flesh-spicule (Spong. Adriat. Meeres, Taf. vii. fig. 17, 
1862), and in the other of a pinlike skeleton-spicule with 
a zigzag or spinispirulate flesh-spicule (Spongienf. atlant. 
Geb. Taf. vi. fig. 18, 1870). This is explained at p. 5 
(ib.) ; but the transition of the acerate to the pinlike skele¬ 
ton-spicule is not mentioned, whereby I should be inclined 
to give a different name to either one or the other ; for if 
we are to follow this reasoning, then Placospongia in spicu¬ 
lation might, but for its other flesh-spicules, be accounted the 
same as Xenospongia —that is, half composed of stellates and 
half of skeleton-spicules, like Hemiasterella. Little, however, as 
the value of the flesh-spicule in specification appears to be under 
these circumstances, it is not so under full development, which 
is the point most useful to remember in specific distinction. 
At the same time, as I have before stated, the form of the 
flesh-spicule, taken alone , when in combination with other 
spicules is not of much value: thus the first form of the 
spiculation of Vioa Johnstonii appears to me to indicate afonn 
of spiculation specifically different from the second ; and while 
the first bears a similar spiculation to that of Hemiasterella 
affi-nis , the second does not do so. Colour has nothing to do 
with it. Lamarck’s Alcyonium purpureum and an undescribed 
species in the Liverpool Free Museum, both different suberitic 
sponges from South Australia, possess a similar spiculation to 
that of the 11 second ” form of Vioa Johnstonii described by 
Schmidt, together with the remarkably beautiful carmine 
colour possessed by the latter. 
I am aware that the terms Holaster and Hemiaster are used 
for species of the Echinodermata ; but I can find no more 
expressive ones for the fossil and recent sponges above described 
than Holasterella and Hemiasterella , in which the terminal affix 
must differentiate the names from those of the Echinoderms. 
EXPLANATION OF PLATE XXI. 
Fig. 1. Holasterella conferta, n. sp. (fossil), natural size. a, head ; b, 
upper part of body; c, lower part; d, stem; e e, dotted hues 
indicating lost portions ; f, puncta representing abodes of crus¬ 
tacean parasites ; </, ends of excretory canals in a broken part. 
Fig. 2. The same. Portion of surface, magnified, to show a a , form of pits 
of crustacean parasites among b , meandriniform grooves and 
pores. Taken from the part marked u h " in fig. 1. 
