OF PISHES EKOM LAKE TANGANYIKA. 3 



proposition enunciated above. Lake Tanganyika might be regarded as the centre of 

 origin of all the African genera of Cichlidce. 



Unfortunately, nothing reliable is yet known of this family in a fossil condition, with 

 the exception of a few American Tertiary types, which do not differ materially from 

 those inhabiting the same part of the world at the present time. There is no reason for 

 referring to it the Cretaceous fishes from Mount Lebanon described as " Chromides" 

 by Heckel 1 and by Davis 2 . All we can gather from Heckel's description is that 

 Pycnosterynx is based on some " Pharyngognath Acanthopterygian," and that it does 

 not belong to the Cichlidce is conclusively proved by his statement : " Rippen kurz, 

 diinn, die hinteren auf langen Querfortsatzeu ansitzend," a sentence that has been 

 translated by Davis as " Eibs short and slender, the posterior ones supporting long 

 transverse apophyses " 3 . An examination of some of the specimens of Pycnosterynx 

 exhibited in the British Museum suggests to me special relation to the Berycidce, with 

 which they are provisionally associated by Mr. Smith Woodward, and certainly no 

 affinity to the Cichlidce. Considering that coalesced lower pharyngeal bones occur at 

 the present day in such widely different groups ns the Serranidce, Gerridce, Scicenidce, 

 Cichlidw, Pomacentridce, Embiotocidce, Labridce, Scaridce, Pleuronectidce, and Scombre- 

 socidce, this character, if correctly ascertained by Heckel, would in itself be no serious 

 objection to the allocation of Pycnosterynx among the Berycidce. Giinther 4 also 

 doubts the correctness of Heckel's determination when he states that " the position 

 of Pycnosterynx is uncertain," but we are not enlightened as to its affinities by the 

 further remark that " it approaches certain Pharyngognaths." It appears certain that 

 true Perciform fishes, to which large group the Cichlidce belong, have not yet been 

 described from pre-Tertiary beds. 



In order to show what is now known of the fish-faunas of the great lakes, lists are 

 appended of the fishes of Lakes Nyassa, Tanganyika, Victoria Nyanza, and Rudolf. 

 These lists must of course be taken as giving a very inadequate idea of the fauna, 

 owing to the incompleteness of the collections on which they are based ; but, imperfect 

 as they are, they nevertheless will prove useful as a basis from which to judge of the 

 relation existing between the piscine inhabitants of these lakes. Of the other lakes, 

 unfortunately, nothing can be said at present, the occurrence of an undetermined species 

 of Haplochilus in the Albert Nyanza being all the information we possess. 



the lower forms. In the Teleosteans, as a general rule, the lateral lines are reduced to one on each side, 

 extending uninterrupted from the head to the root of the caudal fin, although among this order there is 

 hardly a single large group that does not offer exceptions such as are shown in the Cichlidce. In these, both 

 upper and lower lateral lines may be complete ; or the upper may be complete and the lower reduced, or the 

 reverse; or the upper may be incomplete posteriorly and the lower anteriorly, which latter disposition has led 

 to the misconception involved in the term " interrupted." 



1 Abbild. u. Beschr. n. Thier. Syrien, p. 235 (1843). 2 Tr. E. Dublin Soc. (2) iii. 18SS, p. 531. 



3 L. e. p. 532. 4 ' Study of Pishes,' p. 200 (1880). 



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