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



only by one or two examples, which have to be kept intact for the use of future investi- 

 gators, must account for the scanty information which I am able to give with regard to 

 their internal structure. 



In some of the specimens the so-called phosphorescent organs were well enough 

 preserved for microscopical examination, and having always held the opinion that 

 the function of all these organs was to produce light, an opinion which has been partly 

 or wholly opposed by Leuckart, Ussow and Leydig, I was particularly anxious that as 

 much as possible of the materials of the Challenger should be utilized for a thorough 

 histological investigation of these organs by zoologists thoroughly versed in the method 

 of histological research. Mr. Murray acceded without hesitation to this proposal, and it 

 was hoped that Professor Moseley would undertake the whole of this investigation ; but 

 as he was compelled by other duties to limit himself to the examination of the remarkable 

 organs in the genus Ipnops, the remainder were entrusted to Dr. von Lendenfeld. The 

 reports of both these gentlemen will be found in the Appendices to the descriptive 

 report. 



My technical descriptions of the Challenger fishes will be found to be much more 

 concise than those given by some recent writers on similar subjects, and will appear to 

 some to be too short. In my own experience, the practice of circumstantially describing 

 every minute detail of the surface of a fish, repeating every jioint of structure 

 common to all the species of the genus or famdy, and indiscriminately mixing 

 individual features with specific, not only renders the use of these lengthy descriptions a 

 laborious and thankless task, but actually leads to misunderstandings not less frequently 

 than insufficient short diagnoses prepared by inexperienced describers. In fact, in several 

 instances I have found that the descriptions which I published some ten years ago as 

 " preliminary diagnoses," express so fully the specific characters of the fishes as to render 

 any additions to them superfluous. 



