15 

 *3- Placospongia decorticans (Hanitsch) Thiele '). 



S y n o n y m y and 1 i t e r a t u r e. 



Physcaphora decorticans — Placospongia decorticans. 



1895 Hanitsch pp. 205, 214 — 216; PI. XIII, fig. 2 — 3. 



1900 Thiele p. 72 [Physacophora decorticans is apparently a misprint for Physcaphora decorticans . 



1 'lacospongia gr ac ff ei. 



[1894 (5) Lendenfeld p. 115.] 



1897 Lendenfeld pp. 48 — 52, 152, 155, 158, 161, 163, 1S3, 187, 189, 229, 231, 235. PI. VI, 



fig. 48; PI. VII, fig. 61; PI. VIII, fig. 88—92. 

 1900 Thiele p. 72. 



Thiele has pointed out that die sponge described by Hanitsch under the name of 

 Physcaphora decorticans is a Placospongia and identical with Placospongia grac ff ei of Lendenfeld. 

 The latter author in 1S94 only mentioned the name; therefore the specific name cannot be 

 considered to date from 1894 but from 1897 and the name decorticans has consequentlv 

 the priority. 



It seems to us that there can be hardly any doubt as to the specific identity of 

 decorticans and grac f] 'ei: but likewise no doubt, judging from what we know at present, that 

 P. decorticans is a third species, differing from P. carinata and P. nielobcsioides as regards 

 the shape of the sterrospira. 



Carter and Keller are of opinion that Placospongia carinata and nielobcsioides form 

 one species. Herein we differ from them. Both species have the same external appearance and 

 the same general anatomy. Both possess tylostyles and sterrospirae to which may be addeel 

 spherasters. On the other hand P. carinata has numerous parenchymal spinispirae, which 

 are totally absent in P . nielobcsioides, and the dermal spiculum in P . carinata is a microspire, 

 whereas in P. nielobcsioides it is a spherule. Keller says (1. c. p. 326): "Da ich bei dem von 

 mir untersuchten Stück alle möglichen Kieselkörper auffinde, so muss ich die Artberechtigung 

 von P. carinata und P. intermedia bezweifeln und halte sie für Varietaten von P. nielobcsioides." 

 Lindgren (1898 p. 367 — 368) has correctly shown that the "für P. carinata typischen choano- 

 somalen Spiraster" do not occur in Keller's specimen, which he considers as P. nielobcsioides. 

 Keller states further (1. c. p. 325): "auch finde ich bei dem untersuchten Exemplar in ver- 

 schiedenen Schnitthöhen bedeutende Unterschiede," viz. with regard to the spiculation. We have 

 taken the trouble to isolate spicula of some of our specimens "in verschiedenen Schnitthöhen," 

 but we found exactly the same set of spicula. Finally Keller says that transitions between 

 spherules ("Mikrosphaere") and microspirae ("Mikrostrongyle, Stabchen") are not rare ("nicht 

 gerade selten"). In spite of the most careful examination with oil-immersion we never found 

 any such transition. 



1) Species with a s are not represented in the Siboga-Collection. 



