I. Preliminary notes. 



When the collection of sponges from the cruise of 

 the "Michael Sars" was offered to me for examination, 

 I had at first some hesitation in accepting the onerous 

 task on account of the difficulties in consulting the litera- 

 ture and in procuring the material for comparison, which 

 I regarded as absolutely necessary in such a difficult group 

 as the Sponges, especially as 1 had to deal with the 

 Hexactinellida and the Tetractinellida, not previously studied 

 by me. My doubts, however, disappeared, when the well- 

 known spogiologist, Mr. Topsent, most kindly offered to 

 place at my disposal his library and collections in the 

 laboratory at Dijon, and 1 must therefore in the first place 

 heartily thank him for his great kindness and valuable 

 assistance. 



The general results with regard to the sponges ob- 

 tained during the cruise of the "Michael Sars" maybe 

 stated as follows: Of the 24 trawlings only 9 included 

 sponges. 



19 of the 24 hauls with the trawl were made in the 

 eastern part of the southern section of the cruise, and 

 sponges were obtained at 8 stations, while in the northern 

 section with its 4 stations, sponges were found only at 1 

 station in the eastern part. Nothing remarkable with 

 regard to the geographical and bathymetrical distribution 

 has been observed. As the cruise extended mostly over 

 very deep water, Calcarea were not likely to be largely 

 represented, and in fact only one specimen, from st. 102, 

 was taken. The other groups, Hexactinellida, Tetractinel- 

 lida and Monaxonida, were found to be rather evenly 

 distributed over the field of research : Of the Hexacti- 

 nellida 9 species belonging to 8 genera were obtained at 

 6 stations: of the Tetractinellida 8 species belonging to 

 6 genera at 4 stations, and of the Monaxinida, all belon- 

 ging to the suborder Halichondrina, 15 species referred 

 to 14 genera at 7 stations (see the table II). New species 

 were found only among the Monaxonida, and included 

 representatives of the genera Chondrocladia, Stylotella, 

 Echinoclathria, Thrinacophora and Ciocalypta. 



In the classification I have followed Schulze for the 

 Hexactinellida, v. Lendenfeld for the Tetractinellida, 

 Topsent for the Monaxonida, and Dendy for the Cal- 

 carea. With regard to the Monaxonida it ought to be 

 mentioned, that different authors held rather divergent 

 views: Thus while Ridley and Dendy the authors of 

 the first modern system of this group (1887) divided it 

 into 4 families: Homorhaphidae Heterorhaphidae, Des- 

 macidonidae and Axinellidae, Topsent (1894) sets forth 

 in his: "Reforme de la Classification des Halichondrina" 

 another view, dividing the group into 3 families: Haplos- 

 cleridae, Pocilloscleridae and Axinellidae. In 1902 Lund- 

 beck adopted in the main the system -of Ridley and 

 Dendy. Finally in 1911, after his researches on the 

 larval development of different forms belonging to the 

 Halichondrines, Topsent altered his previous system so 

 as to include: Halichondridae, Hoploscleridae, Pocillos- 

 cleridae, Axinellidae (Sur les affinites des Halichondria et 

 la classification des Halichondrines d'apres leurs formes 

 larvaires. — Arch: Zool. exper. et gener. 1910 (5) Tome VII, 

 Note & Rev. No. 1, pp. I.— XV)f 



Accordingly the classification of the Halichondrina 

 seems to call for further investigations of larval develop- 

 ment in order to place it on a sound footing. I therefore 

 have found it most practical to follow Topsent's earlier 

 system, but omitting the arrangement into subfamilies, 

 which as far as I can see can hardly be maintained, in 

 the present state of our knowledge. 



List of species obtained by the "Michael Sars" 

 systematically arranged: 



Calcarea: 



Ordo Calcarea Dendy. 



Fam. Grantiidae Dendy 1913. 



Grantia Intermedia Thacker. 



Silicea: 



Subcl. Triaxonia F. E. Schulze, 

 Ordo Hexactinellida O. Schmidt. 



