518 DR. W. A. CUNNINGTON ON THE 



connection of Lake Tanganyika with the Sea," Moore indicated 

 his belief in the origin of these forms as relicts from a former 

 ocean, by introducing the expression " halolimnic " (126, p. 453 : 

 compare also 138*). Of course from Moore's j^oint of view, a 

 number of animals from other groups — all those, in fact, which he 

 believed to be tlie remains of an old marine fauna — are similarly 

 to be included under the term halolimnic. It is necessary for 

 an understanding of what follows, that the significance of these 

 words should be explained at this point. 



It remains to give a systematic account of what is known of 

 the animal groups represented in the lakes, after which an 

 attempt will be made to draw conclusions from the facts which 

 this detailed study reveals. 



I wish to take this opportunity of acknowledging my indebted- 

 ness to the experts who have so willingly examined and reported 

 on the collections I made in Africa. In a number of cases, too, 

 they have given me valuable advice during the compiling of those 

 sections of this paper on which they are authorities, and for this 

 also I express my thanks. 



3. SYSTEMATIC ACCOUNT AND LISTS OF SPECIES. 



In dealing in systematic fashion with the groups of animals 

 which are reviewed in detail, the latter are arranged approxi- 

 mately in order, beginning with higher and ending with lower 

 types. No attempt is made to conform to any particular scheme 

 of classification, the headings employed being merely such as are 

 sufficient to indicate the contents of the difterent sections. 

 Where certain animal groups are conspicuously wanting, it should 

 be understood that they are either intentionally omitted, as not 

 truly aquatic forms {cf. p. 516), or are unrepresented in the lakes. 

 In each case a list is given (in tabular form where more than a 

 few types are concerned) of the species hitherto recorded from the 

 different lakes, and this is followed by a brief discussion of the 

 points of interest and of the significance of the records. The 

 complete discussion of the zoological evidence and the conclusions 

 to which it points is deferred until the general survey which 

 follows the systematic account. 



Mammalia. 



The biggest, though by no means the most interesting in- 

 habitant of the lakes of Centi'al Africa, is the hippopotannis, 

 which is widely distributed in the tropical parts of the continent. 

 Tlie common species, llip'po'potmnus mnpliihius, is probably to be 



* I do not ag'vee with Moore's subsequent statement that types which are 

 thalassoid cannot be halolininie. It is true that the words are not synonymous, 

 but surely org-auisms may be marine-like in appearanee (thalassoid) and at the same 

 tinie I'eliet tvnes (halolimnic). 



