2 THE VOYAGE OF H.M.S. CHALLENGER. 



flagellated chambers of the sponges. Perhaps I might not have arrived at that 

 conclusion had I not, ten years before, examined a number of Australian arenaceous 

 sponges, which seem to be closely allied to these deep-sea inhabitants collected by 

 the Challenger in different parts of the world. At that time I was engaged with the 

 Monograph of the Medusae, and therefore offered the description of those Spongelidse or 

 Dysideidse to my friend and pupil, Professor William Marshall of Leipsic. He has 

 given a full description and figures in the Zeitschr. f. wiss. Zool., Band xxxv., 1880. 



Dr. John Murray, who, during the cruise of the Challenger, had seen these Deep-sea 

 Keratosa immediately after capture, had at once and rightly recognised their sponge- 

 nature. I find in his handwriting on the labels of the bottles in which all the large 

 forms are preserved the title " Sponges," but afterwards another naturalist crossed 

 this name out and wrote " Large Rhizopods." 



Dr. Polejaeff, of Odessa, commences his Report on the Keratosa collected by H.M.S. 

 Challenger (Zool. Chall. Exp., vol. xi., part xxxi.) with the following words: — "The 

 Keratose Sponges do not belong to the deep-sea fauna." This statement must now be 

 given up in every case. The number of Deep-sea Keratosa described in this Report 

 extends to eleven genera, with twenty-six species, all of which are new, more than half 

 the number (34) distinguished by Polejaeff among the Keratosa collected by the 

 Challenger in shallow water ; of these twenty-one were new. Whilst all these latter 

 belong to genera previously known, the majority of the new deep-sea species belong to 

 new genera, and some of them exhibit such a peculiar organisation that they may 

 represent some new subfamilies, or even families, among the Keratosa. Twenty-three of 

 the twenty-six species were taken in depths between 2000 and 2900 fathoms ; three only 

 (Psamminidse) in depths between 1000 and 2000 fathoms. I suppose that some of the 

 gigantic Foraminifera of the deep sea, which Mr. H. B. Brady has described in his Report 

 as Astrorhizida3 (especially Rhabdammina, Rhizammina, Sagcnella, &c), may also belong 

 to the arenaceous Keratosa (Ammoconida?). 



The results of my examination of the Deep-sea Keratosa, which are given in the 

 following Report, were communicated to the Medicinisch-Naturwissenschaftliche 

 Gesellschaft in Jena on the 14th December 1888. 



