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subsections: “the true asters or euasters, and the streptaster or those 
in which the actines do not proceed from a centre but from a larger 
or shorter axis, which is usually spiral’. Evidently one should 
expect that those #streptasters” were arranged under the “spires.” 
As a matter of fact neither Sorras, nor any other author has 
given very striking arguments to consider the spiraster as a modi- 
fication of the euaster. We know examples of very young stages of 
spirasters; they always possess the twisted character. But no instance 
is known of spirasters originating from or forming transitions to true 
asters. It is true that such supposed transitions are mentioned by 
some authors; but probably we have here to do with a mistake due 
to optical delusion. For instance, Schat described (1862, p. 45) a 
Tethya bistellata, possessing in addition to ordinary asters, double 
ones (/“Doppelsterne’’). But LENDENFELD described (1897, p. 55—58) 
a Spirastrella histellata (which he considers identical with Tethya 
histellata O.S.), in which he found that the supposed asters are true 
Ispirasters”. Judging from what I saw in a type specimen of SCHMIDT's 
sponge, | have no doubt that Lexpexrerp is right. Quite correctly 
LENDENFELD believes that Scumipr has been misled by an optical 
delusion, “da diejenigen Spiraster deren Axen im Preparat aufrecht 
stehen und daher verkürzt gesehen werden, häufig wie Euaster 
aussehen … s.24- I fail to find a single proof that spirasters are modi- 
fied euasters, either in previous papers, or in my preparations. On 
the contrary, everything speaks in favour of the view that #spiras- 
ters” are a sort of e-spiraxons. The fact that in some cases it is 
difficult to get certainty about the twisted shape, is no proof against 
my suggestion in general. For in the great majority of cases the 
twisted nature is certain, as can be demonstrated by allowing the 
spieulum to roll in the preparation when observed through the 
microscope. 
Let us proceed now to examine the different sorts of e-spiraxons. 
1. Sigmaspira. 
Sorras (1888, p. LXID) gives the following definition of the sigmaspira : 
„a slender rod, twisted about a single revolution of a spiral”; he 
adds that it appears in the form of the letter C or S, according to 
the direction in which it is viewed. Te definition of the #toxaspire” 
runs as follows: “a spiral rod in which the twist a little exceeds a 
single revolution. The pitch of the spiral is usually great and the 
spicule consequently appears bowshaped when viewed laterally”.... 
It seems to me not quite exact when Sorzas pretends that the bowshaped 
appearance is in the first place due to the number of revolutions. 
Bhs 
