THE 



VOYAGE OF H.M.S. CHALLENGES. 



ZOOLOGY. 



REPORT on the Deep-Sea Keratosa collected by H.M.S. Challenger during 

 the Years 1873-76. By Ernst Haeckel, M.D., Ph.D., Hon. F.R.S.E., 

 &c, Professor of Zoology in the University of Jena. 



PREFACE. 



The remarkable organisms which are described in the following pages were handed 

 over to me by Dr. John Murray partly in 1887, partly several years ago, when I was 

 occupied with the examination of the Radiolaria collected by H.M.S. Challenge]-. The 

 fact that in the majority of these deep-sea organisms the main mass of the body was 

 composed either of sdiceous Radiolarian tests or of calcareous Foraminifera shells, 

 cemented together by an organic substance, was of peculiar interest to me, inasmuch 

 as it had led to the expression of very different opinions by the naturalists who had 

 previously examined them. Several spongiologists (among them some well-known 

 authorities) had denied their sponge-nature, and declared that these peculiar objects 

 were either Rhizopods or other Protozoa. Other naturalists, on the contrary, who were 

 closely acquainted with the Rhizopods, could not acknowledge their Rhizopod nature, 

 neither could they make out the class to which they belonged. 



A closer comparative examination of these doubtful organisms of the deep sea has 

 led me to the conviction that they are true sponges, for the most part modified in a 

 peculiar manner by the symbiosis with a commensal organism which is very probably 

 in most cases (if not in all) a Hydropolyp stock. At least the majority of the 

 specimens, I have no doubt, are true Keratose Sponges, although the state of preservation 

 was too imperfect for the recognition of all the finer structures, especially the characteristic 



(ZOOL. CHALL. EXP. PART LXXXII. — 1889.) XlUm 1 



