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Tethya bistellata O. S. must be transferred to Hymedesmia, and 
consequently he called it Hymedesmia bistellata (4900 p. 125) 5. 
Now I possess in my collection from Naples a sponge, which is 
beyond reasonable doubt Scumipt’s Tethya bistellata. 1 can affirm 
this especially because the spicules absolutely agree with those of 
a preparation I made at the time in Graz and which is labelled 
“Suberites bistellatus O. S. Origin. Schmidt”. We may suppose, 
therefore, that LENDENFELD, Topsent and myself really examined the 
same sort of spicules, albeit that I must acknowledge that there is 
‘no absolute proof. 
Topsent says, that the microsclera under consideration are euasters ; 
he writes (1900 p. 123) that they are “spherasters de forme parti- 
culiere ... Chacune d’elles résulte de la congrescence latérale de deux 
spherasters a actines nombreuses, coniques, pointues et lisses.’”’ And 
later (p. 127): “les sphèrasters sont doubles. O. Scumipt a insisté sur 
ce caractère important, auquel l’espece doit son nom.” The question 
arises whether Scumipt’s statement is of great value. In 1862 he 
said (p. 45) that some are “ganz eigenthümliche Zwillingsgestalten”; 
and further: “es sind also Doppelfiguren, welche einige Aehnlichkeit 
mit den Euastern haben.” It must, however, not be forgotten that 
ScnMipr at that time was unconcious of the sort of spicula which 
he called later (1868 p. 17) “Spiralsterne” or “Walzensterne’ of 
which he mentions as characteristic ‘dass ihre Strahlen nicht Radien 
eines Centrum sind, sondern in Spiralstellung sich folgen.” 
According to LENDENFELD (1897) are the spicules under consider- 
ation “spirasters’” and he gives some illustrations (1. c. Pl. VI fig. 59) 
which clearly show his conception of the thing. Both from his 
illustrations and from his description it follows that the axis is 
sometimes longer, sometimes shorter. LENDENFELD does not believe 
that ‘“‘euasters” occur and suggests that ScuMipT was perhaps misled 
by an optical illusion. If spicules are examined “deren Axen im 
Praeparat aufrecht stehen und daher verkürzt gesehen werden” they 
simulate euasters. 
In spite of the fact that Torsenr himself remarks, that in minute 
microsclera it is much more obvious that the centre is a line and 
not a point, this author does not consider them as spirasters but as 
double euasters. “Plus elles grandissent, plus la tige d’union se rac- 
courcit. Sur les plus grosses, les deux centrums sont directement 
1) Actually the course of events was this: Topsent (1900 p. 113) writes with 
regard to Tethya bistellata O.S.: “ie l'ai mise à sa place naturelle en 1892.” 
However, in that article nothing is mentioned but the name Hymedesmia bistellata 
without reference to Tethya bistellata. 
