486 PISCES SUB-CLASS IILTELEOSTOML 



is very large. In habits these fish are carnivorous, some of them being pro- 

 vided with powerful incisor teeth, for the purpose of feeding on coral. 



More familiar than the last is the extensive and important family of the 

 wrasses, or thick-lipped fishes, in which the scales have smooth margins 

 (cycloid), and the pouting lips are often greatly thickened. 

 Family Labridce. As in the preceding family, the dorsal fin is single, with the 

 spiny portion at least as well developed as the rayed, which 

 is similar to the anal ; and the pelvic pair are thoracic in position, and com- 

 prise five rays and a single spine. Whereas in some of the wrasses the body 



is deep, in others it is of a more 

 elongated shape. Wrasses are coast 

 fishes, mostly of carnivorous habits, 

 which attain their maximum de- 

 velopment in the tropical and 

 temperate seas. Although their 

 palates are unarmed, their jaws are 

 Fig. 17. STRIPED WRASSE. provided with a number of powerful 



teeth admirably suited for crushing 



the shell-fish on which these fishes chiefly subsist. Sea-anemones or corals 

 afford, however, a preferable diet to some of the species, while a few are 

 strict vegetarians. Wrasses are divided into a number of genera, which may 

 be arranged in larger groups in correspondence with the conformation of the 

 front teeth. In the typical Labrax, of which the headquarters is the Medi- 

 terranean, the jaw-teeth are conical and arranged in a single series. The two 

 British forms are the ballan (L. maculatus) and the striped wrasse (L. 

 mixtus), of which the latter exhibits great sexual differences in coloration. 

 The gold sinny represents in Britain a genus (Crenilabrus) differing from the 

 true wrasses in having the edge of the preopercular bone serrated at all ages, 

 instead of only in the young. 



Passing by many other types, brief reference must be made to the parrot- 

 wrasses (Scarus), deriving their name from the confluence of the anterior 

 teeth to form a cutting beak. One species is common in the 

 Family Mediterranean, where it was well known to the ancients. 

 Diatrematidce. The viviparous wrasses (Ditrema and Heterocarpus) are note- 

 worthy on account of their peculiar reproduction, and are 

 accordingly referred to as a family by themselves. These fishes, which do not 

 attain to a large size, are very characteristic of the temperate portions of the 

 North Pacific, where the majority of the species are confined to the American 

 side, although a few occur on the Asiatic. 



The last group of the Acanthopterygii is the somewhat important family 



of the chromids, which have a very remarkable geographical distribu- 



. tion. From the other members of the group with the lower 



Family pharyngal bones united, they are distinguished by being 



Chromididce. exclusively fresh-water in their habitat. Although none of 



the genera inhabiting the Eastern Hemisphere are common 



to the Western, these fish inhabit the rivers of Tropical Africa, Madagascar, 



Syria, Palestine, and Tropical America, while a single genus is found in 



India. From the other members of the present group, the chromids may be 



distinguished by the absence of false gills. In appearance they are not very 



unlike wrasses, having a single dorsal fin, of which the anterior portion is 



spiny, the scales generally ctenoid, and the lateral line more or less markedly 



interrupted. In regard to diet, they display considerable variation, some 



