PORIFERA. III. 



Expedition, and of digitata from Trieste, Senegal and the Antilles, and I have in these species 

 found the dermal spicules characteristic and constant. T. suctoria has tylota with generally weak 

 and elongated end-swellings, T. digitata has tylota with more or less weak end-swellings bearing 

 some spines on the end, T. tenuicapitata has tornota, and when Ridley and Dendy say (Chall. Rep. 

 Monaxonida, 52), that the dermal spicules in this species may also have round end-swellings, but in 

 a foot-note declare, that such spicules were only found in one specimen, in which also toruotes occur- 

 red, then no doubt a mistake or confusion must have taken place. Finally T. massa has dermal spi- 

 cules which may best be termed strongyla but with a little mucro on the end, and the latter may be 

 quite slightly swollen. 



The rhaphides in the species of Tedania have been somewhat differently understood; Schmidt 

 only mentions them as "feine umspitzige Nadeln'', but does not mention, that they are spinulous; this 

 fact is first stated by Ridley (Proc. Zool. Soc. 1881, 124) in the description of T. tenuicapitata and in 

 the same place the author explains, that such is also the case in a couple of Bowerbank's 

 species [aspera and rudis) and in suctoria O. Schmidt; the author speakes of it as "roughness", and 

 says that it is distinct from "spination" or "microspination". Later the fine spiuulation of the rha- 

 phides is mentioned by several authors as Carter, Ridley and Dendy, Lambe, Topsent, Lind- 

 greu and Thiele. In the four species I have examined, the rhaphides are mainly of the same shape, 

 and they are always finely spinulous in all specimens; I take it therefore as very probable that the 

 TV^-w-rhaphides are always spinulous, and I consider it as certain, that smooth and spinulous rhaphides 

 cannot occur in different individuals of the same species. Ridley describes originally the rhaphides 

 in T. tenuicapitata as "roughened almost imperceptibly", but in the Chall. Report it is declared, that 

 the authors in the specimens which they then had for examination had only found spinulation of the 

 rhaphides in one specimen and moreover only in a spiculum which was not fully developed; I have 

 however examined specimens of T. tenuicapitata from the Challenger Expedition and found the rha- 

 phides spinulous; the spinulation is fine, but rather well distinguishable already by a magnifying 

 power of 300; when the authors have seen the spinulation in a small spiculum, this is easily under- 

 stood, as in the small rhaphides it is most distinct, and, as said above, it is also probable, that the 

 small rhaphides are not developmental stages, but fully develojued spicules. With regard to the rha- 

 phides in T. massa the authors say: "they often exhibit a roughening of the surface. . ."; my exami- 

 nation of the species showed, that the rhaphides are always spinulous. About the rhaphides in T. 

 cmn mixta, infundibuliformis and actiniiformis Ridley and Dendy do not mention whether they are 

 spinulous or not, but as spinulation is not mentioned, it has probably not been seen; it is yet un- 

 doubtedly present Topsent records (Rev. Suisse de Zool. IV, 1897, 454) a T. digitata and says, that 

 he refers it to this species, though it has spinulous rhaphides, which have not been described with regard 

 to T. digitata ; this however is not correct, as Carter already in 1886 (Ann. Mag. Xat. Hist. 5, XVII, 

 52) has declared, that the rhaphides in T. digitata are spinulous. Topsent is therefore of the opinion, 

 that the rhaphides in T. digitata, and on account of the declaration of Ridley and Dendy, also in 

 massa and tenuicapitata and moreover in suctoria, are able to vary, being either smooth or spinulous; 

 according to what has been said above it must be considered as certain, that they are always spinulous. 

 A statement of Dindgren (Zool. Jahrb. XI, 1898, 299) about the variation in the species of Tedania 





