NARRATIVE OF THE CRUISE. 
039 
of the ship. Noctiluca miliaris, various species of Ceratium and Diatoms were always 
present in great numbers, and in addition Copepods, Cirriped larvae, Annelid larvae, 
Hydromedusae, Appendicularia, and Diphyes. 
The Calcarea and Keratosa. — On the return of the Expedition to England, 
Dr. N. Polejaeff, of the University of Odessa, undertook to prepare a Report on the 
collections of Calcareous and Horny Sponges, and his two separate Reports appear in 
the zoological series. 1 Dr. PolejaefF gives the chief results of his investigations in the 
following notes : — “ The adequate discussion of questions bearing upon geographical 
distribution as well as upon the relation of the deep-sea fauna to the fauna of the later 
geological periods is quite impossible as regards the Calcareous and Horny Sponges. Both 
the Calcarea and the Keratosa belong not to the deep-sea, but to the littoral, fauna, the 
greatest depth from which they have hitherto been obtained not exceeding 400 to 450 
fathoms, and even this only in exceptional cases ( Leucosolenia hlanca, var. bathyhia, 
Leuconia crucifer a, Cacospongia levis, Stelospongos longispinus, Verongia tenuissima). 
Again, up to this time, there are in p alee ontological literature no trustworthy statements 
as to their occurrence in the earlier geological periods. The question as to whether the 
Pharetrones, or at least a part of them, are really to be referred to the Calcarea remains 
still open to discussion, and on the other hand the nature of a couple of fossils described by 
Zittel and Carter as Horny Sponges is no less ambiguous. Finally, and with regard to the 
geographical distribution of the two groups in question, it must be noticed that most of 
their representatives in the Challenger collection have been found to present new forms, 
almost every one of which is represented only by a single specimen, so that in this 
respect also no further conclusions and generalisations were possible. Accordingly the 
scientific investigation of the Challenger Calcarea and Keratosa was possible onty from 
a purely zoological point of view. 
“ Apart from the systematic description of new forms, the chief results with regard 
to the Calcarea find their expression in the attempt to frame a new and more natural 
classification than that proposed by Ernst Haeckel in his splendid monograph Die 
Kalkschwamme. The necessity of this measure has been recognised for some years, but 
there was a want of conditions appropriate to its realisation, since the reformer ought 
also to have proved that the phylogenetic ideas on which Haeckel’s system is based are 
false, the execution of this latter task involving, in its own turn, a similar proceeding 
with respect to many of his statements as to the anatomy of the Calcarea in general. 
Of course, numerous contributions to a more correct knowledge of their organisation 
and mutual affinities have long since been made, as for instance the statements of 
F. E. Schulze as. to the impossibility of adopting Haeckel’s strobiloid gemmation hypo- 
thesis of the origin of the Sycones from the Ascones. Again, what we have learned from 
1 Report on the Calcarea, Zool. Chall. Exp., part xxiv., 1883 ; Report on the Keratosa, Ibid., part xxi., 1884. 
(narr. chall. exp. — voL. i.— l88o.) 81 
