REPORT ON THE HEXACTINELLIDA. 183 



of its broad truncated basal plate to a solid substratum, and that the long spicular 

 tuft, whose inferior compact portion is surrounded by the crust of a parasitic p olyi)e, 

 Palytlioa fatua, projected from the narrowed extremity. Passing over his accurate 

 description of the long siliceous filaments, as well as of the elegant, very manifold, small, 

 siliceous spicules of the sponge body proper, we need only here refer to the important 

 observation made by Max Schultze, to the effect that both in the long tuft-spicules, and 

 in the many-rayed or rod-shaped spicules of the body itself, and even in the axial part 

 of the remarkable " Amphidiscs," a fine central canal extends, which is usually intersected 

 at the middle by one or two transverse canals which cross it at right angles. 



While Ehrenberg,' in opposition to this opinion of Max Schultze, still maintained that 

 we had to deal with an artificial Japanese production, von Martens examined the debated 

 organism in Japan, and in the same publication (p. 480) essentially confirmed Max 

 Schultze's opinion. 



A theory of the nature of Hyalonema, similar to that expressed by Max Schultze in 

 his first communication in the Comptes rendus, was expressed some years later by 

 Bowerbank in one of his papers on the Anatomy and Physiology of Sponges.^ 

 Bowerbank united Hycdonema with Halichondria, Isodictya and Spo7igilla, in the 

 suborder of his Silicea. with a " spiculo-reticulate skeleton," — the skeleton being " con- 

 tinuously reticulate in structure but not fibrous." The genus Hyalonema, Gray, was 

 here characterised by Bowerbank in the following manner : — " Skeleton an indefinite 

 network of siliceous spicula, composed of separated elongated fasciculi reposing on 

 continuous membranes, having the middle of the sponge perforated vertically by an 

 extended spiral fasciculus of single, elongated, aad very large spicula, forming the axial 

 skeleton of a columnar cloacal system." 



Siiss in 1862^ called attention to a fossil from the Carboniferous limestone of 

 Yorkshire, which had been already described by M'Coy as Serpula parallela, which 

 exhibited a bundle of from fifteen to thirty or more round, smooth, parallel rods of the 

 thickness of a knitting needle, and each provided with a central canal. This he named 

 Hyalonema parallelwn. 



In 1864 Barboza du Bocage made a communication^ on a new species of the genus 

 Hyalonema, which was discovered off the coast of Portugal at great depths. He named it 

 Hyalonema lusitanicum. Bocage regarded the form and peculiarly regular arrangement 

 of the polypes, which partly surrounded the siliceous spicular tuft and were provided 

 with forty tentacles, as especially characteristic of his new species. His diagnosis runs 

 thus : — " Hyalonema polypario elongato fibris setaceis, hyalinis, spiraliter tortis, corio 

 polypigero ab apice usque ad | longitudinis totse involutis polypis dilatatis, ellipticis valde 

 aggregatis, parum elevatis, per series longitudinales ac spirales regulariter digestis." 



1 Monalsher. d. h. preuss. Akad. d. Wiss. Berlin, 1861, p. 450. ^ pj^n Tram., 1862, p. 1113. 



3 Verhandl. d. h k. zool.-bot. Gesellsch. Wien, 1862, p. 85. * Proc. Zool. Soc. Lond., 1864, p. 266. 



