34 Mr. C. T. Regan — Classification of 



dentition in certain species being subject to variation, accor- 

 din"- to age, or even of a purely individual nature." These 

 remarks led nie to undertake a study of the osteology of the 

 African Cichlida", in the hope of arriving at more precise 

 definitions of the genera and a more natural arrangement. 

 This task was greatly facilitated by the fact that the large 

 Berios of skeletons prepared under Boulenger's direction was 

 available for study. It has seemed convenient to limit this 

 paper to the Tanganyika genera, but a brief summary of the 

 general results may be given. 



Tiie character of most importance in classification is the 

 structure of the apophysis that supports the upper pharyn- 

 gials; the majority of the African Cichlidaj may be divided 

 into those with the pharyngeal apophysis formed by the 

 parasphenoid only (Tihi/>ia type), and those in which the 

 apophysis is formed by the parasphenoid in the middle and 

 the basioccipital at the sides {Haplochromis type). Each of 

 Boulenger's three largest genera (^Tilapia, Paratilapia, and 

 Ptlmatocliromis) contains species of both groups, and the 

 majority of the species in each with the llnjAodiromis type of 

 apojihysis may be added to Naplochromisj which thus becomes 

 the largest African genus. J\lost of the other genera can be 

 definitely assigned a position as either related to Tilapia 

 {l^arutihtpia, Pelmalochrotnis, lleiuitilapia, etc.) or to JJapio- 

 chroviis (Heniichrovn'<y Charvpsochromis, Q'c). All the 

 American Cichlidse (except Cielda, which resembles llaplo- 

 chromis) have the j)liaryngtal apoj)hysis formed as in Tdu]>ia. 

 In order to give satisfactory definitions and to express the 

 api)arent relationships some new genera must be created. 



Synopsis of the Tanganyika Genera. 



I, Posterior part of parasphenoid -n itb a strong apophysis endinp in 



a flatti.sh trianiiular or broadly ovate surface lor articulation of 

 upper pharyugeald. 



Teeth in jaws conical. 1). XIII-X VI 12-17. 

 A. Ill 7-y. Scales 30-GO ; lower lattsral 

 line extending fur forward 1. Tylochromt^, 



II. Posterior part of parasphenoid slightly or moderately raised, 



bearing a pair of more or less distinct circular or oval facets fur 



articulation of upper pbaryngeals. 



A. -Mouth terminal ; teeth in jaws pluriserial, all tricuspid, or outer 



mo,stIy bicuspid. Ethmoid unconnected with vomer ; inferior 



apojiliyses oi' third vertebra imited to form a strung spine. 



1). XV-XVIII 11-16. A. Ill S-11. Scales 31-36. 



Outorniost series of teeth mostly bicuspid .... 2. Tilapia. 

 'I'efth all slender, tricuspid 3. NcotUapiu. 



