FISHES. 171 



About one hundred and forty species are now known, from tlie sti'eams and brack- 

 ish lagoons of the eastern United States, tropical and South America, Africa and Asia. 

 Few are found in Europe, and few in the nortli Pacific region, and none mucli north of 

 the latitude of Boston. The majority frequent brackish lagoons, lowland swamps, and 

 mouths of rivers, but the strictly fresh-water species often abound in the clear fountain- 

 lieads of streams. Some African sj)ecies live in hot springs. 



The species are all of small size, some of them {Ileteratidriu) being the smallest known 

 vertebrates. The largest species (AnaMeps, J^undulus) seldom reach the length of a 

 foot. In most species the sexes are dissimilar, and in several genera the anal tin of the 

 male fish is modified into an intromittent organ, whereby the ova are fertilized before 

 exclusion. Such species are ovo-vivipai'ous, the young being developed in a sort of 

 uterus, and being born at a com])aratively advanced stage of growth. At birth, they 

 closely resemble the adult fish. Most of the viviparous species feed upon mud ; the 

 others upon insects and small organisms. The majority are surface fishes, swimming 

 about slowly, with their eyes partly out of the water. Others ( Ci/jjrinodon, Fundulus) 

 are more active, and keep near the bottom, but always in very shallow waters. None 

 of the species have any economic value. All are very tenacious of life. 



Of the numerous genera, the following are some of the most noteworthy. The 

 genus Cyprinodon comprises numerous chubby little fishes of the shores of America 

 and southern Europe, provided with tricusjiid incisor teeth. They are ovijiarous and 

 carnivorous. Similar to these, but 

 with a long dorsal fin and a general " 



resemblance to young sun-fishes, is ^=^g;t^^ r==^-^^^ ^ ^ ^^= 



the genus Jordanella of the lakes ' --^s^- - - ^^^^— 



and everglades of Florida. Most - / _ ^g 



of the larger species belong to thi' 



genus Fundulus, which is widely i 



distributed both in fresh waters /^^ -J "^^ 



and in salt. The largest North _ -. ""^g 



American species is Fundulu)< 

 majcdis ; the most common, Fun- 

 dulus heterocUttes. 



Of the genera with modified 

 anal, and consequently ovo-vivipa- 

 rous, we may notice Gambusia. 

 One species of the genus {Gambusia patruelis) abounds in all swamps and brooks of 

 the lowlands of the south, and brings forth its brood in early spring. The males are 

 smaller than the females and are much less numerous. 



Allied to Gambusia are MolUenesia, with large, banner-like dorsal fin, Pacilia, 

 with smaller fins, Xip^iophorus, with a sword-shaped lower lobe to the caudal, Goddea, 

 with tricuspid teeth, and Ileterandria with small teeth in a single row. Heteraiidria 

 formosa, a pretty little fish of the southern lowlands, is said to be the smallest of 

 fishes, rarely exceeding half an inch in leiirrth. 



The most curious of the Cyprinodontid;e is the genus Aii<d)hps of the streams of 

 tropical America. These are surface-swimming fishes, like Gambusia and Zygonectes. 

 The prominent eye is divided by a horizontal partition into two parts, the upper 

 adapted for vision in the air, the lower in the water. These fishes reach a length of 

 more than a foot, being the largest of the Cypiinodontidae. 



Pig. log. — Gambusia iMlnnlig, top i 



