PREFACE. 
— ♦ — 
In completing the present account of the researches which were 
undertaken during the two Tanganyika expeditions, I am somewhat 
oppressed with the possibility that the unique opportunities and 
material available may not have received the justice they would 
have done in the hands of many naturalists who have more ex- 
perience than I am old enough to possess. We were actually the 
last zoological explorers with a great untouched field before them, 
and when it is remembered, that among other things, we have had 
to deal with nearly 200* entirely new animal types discovered 
during these expeditions, it will be admitted that the labour of 
giving an adequate account of the faunistic characters of the 
great African lakes has not been exactly child’s play. It should, 
moreover, be clearly understood that the acquisition of all this 
new material and information respecting Central Africa has been 
primarily due to the instigation and persistence of Professor Ray 
Lankester, and I only wish that he, instead of myself, could have 
found time to write the present account. On the other hand, it 
would perhaps have been impossible for anyone who was without 
a somewhat prolonged and actual acquaintance with the African 
interior, to attempt to deal with all the aspects the Tanganyika 
problem has been found to present, and I can therefore only point 
out to any who may feel that the present work could have been 
better done, that I am fully conscious of its peculiar deficiencies. 
Few people here, moreover, will be able to appreciate how com- 
pletely during the actual operations of exploring parties in practically 
unknown countries, whatever results may be obtained are due to 
the disinterested and gratuitous help which may or may not be 
extended to them by people, administrators and the like, who live 
* In this connection it may be interesting to remember that the whole of the fishes, 
fresh water and marine, belonging to the British Islands, only represent about 240 
species. 
