576 FISHES. 



Twelve species of this genus are known ; they are small, 

 and similarly distributed as Doras, with which they have 



Mg. 265. — Calliohthys armatus, from the Upper Amazon. Natural size. 



much in common as regards their mode of life. They like- 

 wise are able to travel over land, and construct nests for 

 their ova. 



Ch^tostomxjs. — A short adipose fin, supported anteriorly 

 by a short, compressed, curved spine ; dorsal fin of moderate 

 length, with from eight to ten rays, the first of ■which is simple ; 

 anal fin short ; ventral six-rayed ; pectoral with a strong spine. 

 Head and body completely cuirassed, the lower parts being 

 sometimes naked ; body rather short, with four or five longi- 

 tudinal series of large imbricate scutes on each side ; tail not 

 depressed. Snout produced, obtuse in front ; mouth inferior, 

 transverse, with a single series of generally very fine bent teeth 

 in both jaws. Interoperculum very movable and armed with 

 erectile spines. 



This genus, with the allied Plecostomus, Idposarcus, Ptery- 

 goplichthys, Bhinelepis, Acanthims, and Senomystus, is well 

 represented in the fresh waters of South America, whence 

 about sixty species are known. The majority do not exceed 

 a length of twelve inches, but some attain to more than 

 double that size. In some of the species the male is provided 



