CHAR A C I NO IDS. 



469 



distributional areas. It is, however, not a little remarkable that whereas in their 

 migration to Africa they have been accompanied by members of the carp tribe, 

 in Tropical America they entirely take the place of that family. The numerous 

 genera, none of which are common to the two hemispheres, are ranged under 

 eleven groups or subfamilies, the majority of which are confined to either the one 

 or the other half- of the distributional area, although a few have representatives 

 of both. As regards their habits, some of these fishes are strictly carnivorous, 

 while others are as exclusively vegetable-feeders. 



The figured species belongs to the last subfamily, which includes four exclus- 

 ively American genera, represented by some forty species, and characterised by the 

 somewhat elongated dorsal fin, behind which is a small fatty fin; by the gill- 

 membranes being free from the isthmus, and also by the distinct serration of the 

 middle line of the under surface of the body. 



On account of their large size, two other genera of these fishes, which have 

 respectively received the names of Hydrocyon and Cynodon, must be mentioned ; 



THE PIRAYA ( nat. size). 



the former being from Tropical Africa, and the latter from Brazil and the Guianas. 

 They grow to the length of 4 feet, and are highly predacious ; the subfamily to 

 which they belong being characterised by the presence of a short dorsal and anal 

 fin, the large conical teeth, the want of attachment between the gill-membranes 

 and the isthmus, and the approximation of the nostrils. 



THE CYPRINODONTS, Family CYPRINODONTID^:. 



The small fishes which, for want of an English title, we may designate 

 3yprinodonts, bring us to the first family of another sectional group termed the 

 Haplomi, which also includes the pikes. In addition to certain other structural 

 features of the skeleton, this group is characterised by the first four vertebrse being 



