18S6.] POSITION AND CLASSIFICATION OF SPONGES. 559 



Whilst the anatomical and embryological work of recent authors, 

 particularly of F. E. Scbulze and his pupils, has made us acquainted 

 with the structure of Sponges in a satisfactory manner, our know- 

 ledge of species, which was formerly practically confined to those 

 from the Mediterranean and the Atlantic, has been greatly extended 

 bv the collections made during the voyages of the 'Alert' and 

 'Challenger' in all parts of the world, and by ray own labours in 

 the Australian seas. 



I think, therefoie, that the time has now arrived to endeavour to 

 establish a classification of Sponges, and to discuss the position 

 which the Sponges, as a group, occupy in the scale of Nature. 



In an Appendix to this paper a nearly complete list of publications 

 on Sponges is given. It has been made by interpolating old, new, 

 and omitted papers in D'Arcy Thomson's (1495) list of 551 jjapers, 

 the references in which have been verified. I must express my 

 thanks to Mrs. v. Lendenfeld and to Mr. A. Dendy for their share in 

 this work, and also to Mr. Ridley for his kindness in allowing us 

 to use his most valuable MS. notes on this subject. 



In the section on the systematic position of Sponges, the principal 

 views held on the subject are discussed, and reasons are given for 

 considering the Sponges as the first Phylum of the Grade Ccelentera, 

 which arrangement has been adopted in this paper. 



The main classification of the Orders is the result of my own anato- 

 mical work, and has been arrived at independently of other authors. 

 It affords me much pleasure to state that this classification is, in the 

 main, similar to that established by Vosmaer (1550), although we 

 have arrived at our results in different ways, and our diagnoses 

 differ accordingly. 



To that section of this paper which deals with the arrangement of 

 the Families and Subfamilies, and the enumeration of the principal 

 Genera, Mr. A. Dendy has contributed the portions relating to the 

 Suborders Clavulina and Hahchondrina with the exception of the 

 Tethydae and Chalininse. The portions relating to the Hexactinellida 

 and Tetractinellida are compiled from the recent papers of Schulze 

 (1369), Sollas (1453), Vosmaer (1550), and Zittel (1639). The 

 remainder is based on my own MS. notes. 



II. Nomenclature of the Spicules. 



Various terms for the spicules found in Sponges have been used 

 by different authors. In consequence of this a certain confusion 

 has arisen with regard to the meaning of the terms employed. 

 Vosmaer(1550) made a chivalrous attempt to establish a satisfactory 

 Nomenclature, which, however, has unfortunately not been accepted 

 by recent authors on Sponges except myself, so that it only added 

 to the already existing confusion, 



Recently Sollas, Ridley, and Dendy have established a new nomen- 

 clature for Monaxonid spicules, whicii I have agreed to adopt, and 

 which has been used by them and myself. I do not think it perfect, 

 but I am certainly not in a position to replace it by anything better, 

 and therefore adopt and explain it in this paper. Schulze's nomen- 



