and Acapulco Sponges. 347 



Hab. Marine. Burrowing in hard calcareous objects. 



Loc. Island of St. Vincent, West Indies. 



Ohs. The characters generally of this sponge are almost 

 identical with those of our Cliona celata, when burrowing in cal- 

 careous objects ; but the globular form of the head of the skeletal 

 spicule, taken on an average, and the presence of the flesli- 

 spicule cause it to differ. Whether or not Cliona cariblxaa 

 ever occurs in Sifree state analogous to Rhapht/ncs Oriffithsii, 

 Bk., which is that taken by C. celdta after having completely 

 destroyed the oyster-shell in which it may have been burrow- 

 ing, must be determined by further research. 



General Observations. 



Here it may be stated that, without mounting a micro- 

 sco})ic frangment of this sponge in balsam, the fiesh-spicules, 

 from their extreme delicacy, would pass unnoticed ; and such 

 is the case with many other sponges of this kind, in which 

 the minute size and crooked spinispirular form of the 

 flesh-spicule render the latter difficult of detection until the 

 sarcode is made clearer and more homogeneous by drying 

 and subsequently mounting in Canada balsam. At the same 

 time it must be remembered that the flesh-spicules are chiefly 

 confined to the surface in many instances, and therefore may 

 not be seen in a fragment from the interior, also that they do 

 not exist in all these sponges ; hence the necessity of deter- 

 mining these points in the way that I have mentioned. 



The spinispirula in the Suberite sponges, by which is 

 meant those in the groups Cavernosa, Corapacta, and Laxa, 

 was first noticed by Dr. Bowerbank in 1864 (Mon. Brit. 

 Spong. vol. i. pi. iii. fig. 72), when, together with an un- 

 spined spirula {ibid. fig. 71), it was found inadvertently in 

 Halichondria sanguinea, Johnst. {tb. p. 239), where he con- 

 sidered them to be of " extraneous " origin ; but when we 

 remember that no sponge, in texture and spiculation, is more 

 suberitic, i. e. cork- like, than a dried H. sanguinea^ the presence 

 of such spicules there does not seem strange ; but it is strange 

 that the identical form of this spinispirula should be repeated 

 eight years afterwards (Proc. Zool. Soc. 1872, pi. xlix. fig. 7) 

 as the type spicule of a large free massive Suberite of an ochre- 

 yellow colour from Madeira, called by Dr. Bowerbank 

 " Hymeniacidon angulata^^ when one from the sponge itself, 

 with the slightest difference (for there are no two spinispirulas 

 exactly alike), would have been much more satisfactory. 



In 1864 also, Schmidt gave a good figure of a spinispirula 

 (Spong. Adriat. Mceres, 1st Sujipl. Taf. iv. fig. 12) from a 

 " corticate " sponge (liindsehwamm) from the island of 

 Cyprus, but without any further notice. 



