Studies on Sponges. 



By 

 Dr. G. C. J. Tosmaer. 



Assistant at the Zoological Station. Naples. 



I. Oll Velinea gracilis ii. g. ; ii. sp. 



With Plates 31 and 32. 



Two years ago I founcl in the Collection of the Zoological Station 

 a curious species of Sponge, to which I alluded in my report to the 

 Dutch Government ^ 



The Sponge in question was dredged in the Bay of Naples, biit I 

 did not obtain any indication of the depth . It consists of a colony of 

 cylindrical tubes, the whole being about 9 cm in height. The colour, in 

 spirit, is a yellowish-brown. The slender, rather compact, tough, tubes, 

 with their terminal oscula gi ve to the Sponge the appearance of a siliceous 

 Sponge, so that at first sight oue would think to have to do with some- 

 thing allied to Siphonochalina (fig. 1). 



In observing the Sponge with a lens we see over the whole surface 

 little elevations , due to more or less protruding hörn - fibres (fig. 2) . 

 These give the Sponge, for which I propose the name Velinea gracilis, 

 the appearance of shagreen, if seen with the naked eye. Between the 

 ends of the fibres are to be seen the pores, being, as is usuai, the en- 

 trances of the canalsystem. These pores are not very frequent and 

 vary considerably in diameter (fig. 3); the water, having passed 

 through them, comes in the so called subdermal-cavities, these being a 

 system of lacunae just under the dermis. I cannot say whether these ca- 

 vities communicate all together, but I am sure that a number of the holes 

 as they are visible in sections [s.cl.c. in the figures) do communicate. 



1 G. C. J. VoSMAER, Voorl. berigt etc. in Ned. Staatscourant No. 109. 1881. 



Mittheiliingen a. d. Zoolog. Station zu Neapel. Bd. IV. 29 



