QQ Miscellaneous. 



tively, and consequently can be applied to the establishment of the 

 higher systematic groups. O. Schmidt's principle of division there- 

 fore applies also to the Australian sponge-fauna, divergent as it 

 may be. 



0. Schmidt has so far accepted a polyphyletie pedigree for the 

 Chalinida? as to derive the sponges with axial siliceous spicules in a 

 network of horny fibres in part from the horny sponges and in part 

 from the Renieridse. I am in a position to describe a continuous 

 series of forms which lead from the Ceraospongiae to the true Renie- 

 ridffi without any horny matter. There are all steps between the 

 skeleton of the ChalcajnidDe, consisting of spicules arranged in 

 bundles and combined into thick cords, and the tissue of the typical 

 Rcnierida;, with its loose triangular meshes. Thus I possess a 

 whole series of sponges the skeleton of which consists of parallel 

 cords, representing the main fibres of the horny sponge. These 

 cords consist of a dense mass of siliceous spicules, and are united 

 with each other by single spicules of the same form, representing 

 the uniting fibres. Tliey are consequently separated from each 

 other by the length of a spiciile. In some of these sponges the 

 main fibres are feeble and often bent, so that the looser Renierid 

 tissue is formed by the weakening first of the uniting fibres and 

 then of the main fibres of the Chalca3nidae. The Australian Renie- 

 ridae, however, show no relationship with the l^lyxospongije, from 

 which they must have been derived, if not from the Chaliuida?. 



Our sponges show that the non-ceratose Monactinellida? represent 

 the terminal members of a series which starts from the Cerao- 

 spongise. The spicules of the Monactinellidce are either uni- or 

 biradiates. (In this the biacuates ac" and ac ac, Vosmaer, are re- 

 garded as biradiates, and the obtuse-ended, tubercular, and pin-like 

 forms tr ac, tr° ac, tr ac sp, Vosmaer, as uniradiates.) In agree- 

 ment with F. E. Schulze, I regard the pluriradiate form as phylo- 

 genetically older. 



I regard the spicules formed in the parenchyma of the sponge, 

 the flesh-spicules, as in every respect essentially different from those 

 which were deposited in the axes of the horny fibres, originally 

 as biradiates, in the ancestors of the Chalinidae. By reduction of 

 the number of rays the obtuse-ended spicules have thus been deve- 

 loped from the biradiates, and from these again the pin-like and 

 tubercular forms. In many cases a gradual disappearance of the 

 horny substance takes place j:»flri passu with the transformation of 

 the spicules, while in other cases again the spongioline disappears 

 without the spicules changing their form. 



If we now consider the Monactinellidae from this point (for the 

 present without reference to the flesh-sincules), we obtain the 

 following classification, in which they form as a whole an order 

 " Monactinellidse " in the class of Sponges : — 



