G2 Mr. C. T. Regan on the Fishes of the 



Prsemaxillary processes shorter than the head; maxillary 

 exposed or not. Upper surface of head scaly to the level of 

 the orbits or beyond ; cheeks and opercular bones scaly ; 

 prseoperculum entire. Gill-rakers rather short and few 

 (6-15 on the lower part of anterior arch). A single dorsal 

 fin, with XIV-XIX 7-15 rays ; no notch between spinous 

 and soft portions. Anal with IV-XII 6-14 rays. Pectoral 

 asymmetrical, Avith 12-18 rays; ventrals below or a little 

 behind the base of the pectorals. Caudal rounded, truncate 

 or emarginate. 



Numerous species from Mexico, Central and South 

 America. 



I have examined the skeleton in four species, in which 

 the number of vertebrae is as follows : — 



C. guttulatum . . . . 14+16 = 30. 



C. tetr acanthus .... 13 + 15 = 28. 



C. octofasciatum . . . . 13 + 16 = 29. 



C. Salvini 13 + 15 = 28. 



The ribs are subsessile. The supraoccipital crest is high 

 and extends forwards on to the f rentals, whicli are hollowed 

 out anteriorly for the reception of the prsemaxillary processes. 

 In C. (juttulatum and C. octofasciatum these are compara- 

 tively short and the supraoccipital crest extends forward 

 nearly to the level of the anterior margins of the orbits. In 

 C. tetr acanthus and C. Salvini the prsemaxillary processes 

 are longer and the supraoccipital crest terminates above the 

 middle of the orbits. The parietal crests are well developed 

 and extend forward to above the middle of the orbits. The 

 ])elvic bones do not diverge anteriorly. In C. tetracanthus 

 the lower pharyngeals are strongly developed, they are 

 firmly united by a very sinuous suture, and bear large obtuse 

 teeth ; the fourth vertebra bears a moderately developed 

 inferior apophysis. In the other three species the suture 

 between the lower pharyngeals is straight, the teeth are 

 pointed, whilst the inferior apophysis is feeble or wanting. 



The genus Cichlosoma stands in the same relation to Acara 

 that the African Laniproloyus does to Parati/ajna, and, as 

 far as external characters are concerned, it is more difficult 

 to distinguish between Cichlosoma and Lamproloyus than 

 between Acara and Paratilapia. C. Dovii, for example, 

 presents considerable similarity to L. congolensis in general 

 form, structure of the fins, structure of the mouth, dentition, 

 &c. The most notable difference is that in Lamproloyus the 

 scales on the cheeks and opercular bones are usually 



