4i8 



SPINY-PINNED GROUP. 



THE WRASSE-LIKE FISHES, Families POMACENTRID^ 



CHROMIDID^E, etc. 



In almost all the families of spiny-finned fishes hitherto described the lower 

 pharyngeal bones are completely separated from one another, whereas in the 

 four families remaining for consideration these are united with one another. It 

 has been considered that this difference was of sufficient importance to justify 

 the reference of the families with united pharyngeals to a subordinal group of 

 equal rank with one containing those in which these bones remain distinct ; but we 

 prefer to follow Day in regarding the group now to be considered merely as a section 

 of the suborder which includes all the other spiny-finned fishes. That this is the 

 correct view is proved by the circumstance that in one aberrant genus of perches 



SILVER-DOTTED POMACENTRUS (| liat. size). 



(Gerres) some of the species have the lower pharyngeal bones separate, while in 

 others they are united. In the three families constituting the present group 

 there is a single dorsal fin, in which the number of spines and soft rays is 

 nearly equal ; while the anal is usually similar in character to the soft dorsal ; 

 and the pelvic fins are thoracic in position, and include one spine and five 

 soft rays. 



The first of the families of the present sectional group takes its 

 name from the genus Pomacentrus, which, together with the allied 

 genera, includes tropical fishes mainly frequenting the neighbourhood of coral- 

 reefs and islands, and thus closely resembling the scaly-finned fishes (p. 343) 

 in their mode of life ; a few species of the family range, however, into the seas 

 of the temperate zones. As an example of the typical genus, we figure P. scolopsis, 

 from the Malayan seas and Polynesia. As a family, these fishes are specially 

 characterised by the presence of false gills and ctenoid scales. In form, the body 



Pomacentrus. 



