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



Dr. Giinther, F.R.S., the Keeper of the Zoological Department, for the facilities which 

 they have placed at our disposal while working in the Museum, and for the use of the 

 rich national collection, without which it would have been scarcely possible to carry on 

 the work. 



We are further under great obligations to Professor A. M. Marshall, F.R.S., of the 

 Owens College, and to the authorities of the Normal School of Science and Royal School 

 of Mines, especially Mr. G. B. Howes, F.L.S., for kind permission to make use of their 

 laboratories and appliances for purjaoses of anatomical and histological investigation. 



With reference to his share in the preparation of this Report Mr. Ridley desires to 

 add the following note : — 



" Works like the present, produced by a joint authorship, differ in some respects 

 from those otherwise produced, and I wish to say a few words with regard to my own 

 connection with the Report, and especially to the views expressed in it. 



" At the time at which it became necessary for another worker to share the labour in 

 order satisfactorily to complete the work, I had done no more than study as carefully 

 as my somewhat limited time and means allowed the classificatory characters of 

 most of the species, and in a few cases also their minute anatomy and histology, and 

 had decided on the novelty or the nomenclature (in the case of the old species) of most 

 of the forms below treated of The results thus obtained proved to require considerable 

 modification, and the credit of presenting the work in its present form is mainly due to 

 Mr. Dendy, who has studied afresh all the species and mastered their characteristics, 

 besides undertaking by far the greater part of the labour involved in the ' production ' 

 of the Report. 



" With regard to theoretical views, where any such are referred to in the following 

 pages, either explicitly or by implication, my own j^osition is that references to 

 'affinity,' 'genetic relationship,' 'development' 'acquisition,' &c., are only to be 

 taken, so far as I am individually concerned, as convenient methods of expressing the 

 phenomena presented to us, and as involving merely hypothetical interpretations of the 

 processes which may be conceived to have taken place in the past history of these 

 organisms ; the theory of evolution appears to me to give an extremely reasonable and 

 very possibly true, but as yet not fuUy demonstrated explanation of these phenomena, 

 except, perhaps, in the case of some book-species, which ought not to be separated 

 from each other. I hold the view that ' theories are convenient bases on which to 

 group facts,' but further consider that facts acquire an additional interest when they 

 are studied with the object of testing theories, and perhaps attain their greatest 

 importance when it is possible to use them inductively, viz., for the construction or 

 confirmation of general laws." 



