36 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. V. 



Family V. Cypriiiiclse. 



THE MINNOWS. 



Body elongate, more or less compressed; mouth large or small, ter- 

 minal or subinferior; margin of the upper jaw formed by the premaxil- 

 laries; no teeth in the jaws; pharyngeal bones well developed, falci- 

 form, and nearly parallel with the gill a,rches, each provided with i to 

 3 rows of teeth, usually 4 to 7 in the main row; fewer in the other rows 

 if present ; barbels usually none, never more than 2 to 4 ; belly rounded, 

 rarely compressed to an edge, and never serrate; gill membranes 

 broadly joined to the isthmus; branchiostegals always 3; gills 4; 

 pseudobranchiae usually present; ventral fins abdominal; air bladder 

 large, usually in two lobes; stomach without appendages. 



This family comprises many small fresh -water fishes. A few of 

 our western forms reach a large size. On this continent the south- 

 ernmost limit of this family is in the Balsas basin in southern Mexico. 



This large group of small fishes which so much resemble each other 

 in form, size and coloration is one of the most difficult in which to dis- 

 tinguish genera and species. Before one can make much progress in 

 the study of these species, careful attention must be given to the 

 teeth, as the genera are based largely on dental characters. The teeth 

 are confined to the pharyngeal bones which are just back of the gill 

 openings on either side of the oesophagus. In American species the 

 teeth on each pharyngeal bone are in one large row of 4 or 5, in front 

 of which is usually a smaller row of one or two teeth. The pharyn- 

 geal bones must be removed with great care to avoid breaking the 

 teeth from them. It is best to clean the teeth by tearing away the 

 flesh with a needle or other sharp-pointed instrument, after which 

 they are easily examined with a hand lens. The herbivorous species 

 have teeth usually not hooked and with a flat or concave surface. 

 In the carnivorous species they usually have a sharp cutting or a ser- 

 rated edge and hooked tips. Their number is indicated by a dental 

 formula. Thus "teeth 4-4," indicates that only the principal row is 

 present. "Teeth 2, 4-5, 2," indicates the principal row on one side 

 contains four teeth, the other five, while the lesser row on each side 

 contains two each, and so on. 



During the breeding season the males are more or less covered with 

 tubercles, outgrowths of the epidermis. Usually these are, confined 

 to the head, but often are found over the entire body. The lower 

 parts of the body and the fins are often highly colored ; the prevailing 

 color being red, although in some genera it is satin white, yellow, or 

 black. In some cases the males are deeper than the females. Young 

 examples are always difficult to identify; these are usually more 



