THE AQUATIC VERTEBRATES 



1047 



them attached to the ventral surface. Several African and South 

 American Cichhds carry the eggs and young in their mouths and 

 gill chambers. The so-called myth, that a given lish leads about 

 his brood and guards them in his mouth when danger approaches, 

 is not a myth for some of these species. 



The bhnd fishes of North America carry their eggs in their gill 

 chambers. In these fishes the o\dduct has moved forward so that it 



Fig. 1542. Rainbow D-drti^r, Et/wostoma cacrulcum Storer, $ . 



opens just behind the isthmus. The young are carried for a month 

 or two until they have reached a length of 10 mm. In a group of 

 Cyprinodonts reaching as far as Indiana, but increasing in diver- 

 sity of species and numbers of individuals southward, the eggs are 

 retained by the female until the yolk is absorbed by the growing 

 young fish, and sometimes for a much longer period. In the 



.^ 



Fig. 1543. Uainhovi D[irtcr, Elhetntomii caerulcum Storer, 9- Actual size, 50 mm. 



bhnd fishes of Cuba the young are about an inch in length at the 

 time of birth and in the California surf-perch they may be twice 

 as long. 



Secondary Sexual Characters. — Such features consist in size, 

 disposition, color, or structure. Large differences in all of these 

 are found in the kilHfishes. In some of these species the male 

 is minute and provided with an anal fin modified into a lance- 



