258 MR. J. Y. JOHNSON ON A NEW SPONGE. [JuilC 23, 



Dactylocalyx bowerbankii, sp. n. 



The skeleton of this sponge is composed of an inelastic network 

 of silex of a dense and irregular structure. Under a power of sixty 

 diameters a slice of it resembles the crumb of bread, without any 

 trace of the structure resembling spoked wheels, such as is exhibited 

 by a siliceous sponge preserved in the Museum at Paris under the 

 name of Iphiteon — a similar structure being also seen in the pith of 

 some water-plants. The fibre is smooth, but somewhat nodulous. 

 The skeleton is covered with a rather thin crust, of a close texture, 

 without conspicuous orifices, and this crust abounds with large 

 spicula of the form denominated "spiculated patento-ternate" by 

 Dr. Bowerbank in his memoir read before the Royal Society in 1857 ; 

 and some of them are developed into the dichotomo-patento-ternate 

 form, such as is represented in fig. 48 of plate 23 of the ' Philoso- 

 phical Transactions' for that year. But in the sponge under de- 

 scription the shaft is not prolonged through the common base of the 

 triradiating branches, and the second division of these branches is 

 much longer than the first or third ; the third division, or ultimate 

 branchlets, are pointed, and not in the same plane with each other 

 or with the preceding portion of the branch, just as in the case of 

 the spiculum represented in the figure already referred to. The 

 shafts of the spicula project into the reticulations of the skeleton. 

 In addition to the large spicula, the dermal membrane abounds with 

 minute elongo-stellate spicula having short stout cylindrical radii ; 

 and a very few of these are dispersed in the interstitial membranes 

 beneath the dermis. On the surface of the skeleton, immediately 

 beneath the dermis, there is an abundance of long acuate spicula, dis- 

 posed either singly or in fasciculi which are often parallel with each 

 other. These acuate spicula are not found in the deeper interstitial 

 portions of the sponge, but a few long, very slender, and flexuous 

 spicula are occasionally to be found there. No sexradiate spicula 

 could be detected, nor were any gemmules observed. 



The single example of this sponge which has been obtained was 

 brought up from deep water off the coast of Madeira. It was at- 

 tached to a rock or stone by the middle portion of the underside. 

 Its colour is white ; and although its texture even when fresh was 

 firm, the finger-nail easily made a permanent impression upon its 

 surface. The animal matter was in comparatively small quantity. 

 When a portion of the sponge was immersed in nitric acid it acquired 

 a yellow tinge. The shape is that of a concave disk or shallow cup, 

 with the border undulated into a few strong folds, some of which 

 rise two or three inches above tlie rest of the surface. In one instance 

 the opposite sides of a fold have grown together. The general ap- 

 pearance calls to mind a large fungus such as is sometimes seen 

 attached to the trunk of an old tree. It measures fourteen inches 

 across in one direction, in another twelve inches, and it has a thick- 

 ness varying from half an inch to nearly an inch. 



Dr. Gray has had the kindness to let me examine the half of a 

 siliceous sponge which came into his possession from Mr. Stutchbury, 

 who obtained it, I understand, from Barbadoes, and described it in 



