THE CYPRINODONTS. 



The " Cyprinodonts," " Top minnows," or " Toothed Carps," as they are 

 variously called, form a well defined group. An average of their shapes 

 would approach that of a common Gold Carp with the tail rounded instead 

 of notched. The species resemble the Carps, Cyprinidce, in form, possession 

 of a single dorsal fin, absence of a pouch on the stomach, lack of pyloric ap- 

 pendages, and in other features ; but they are readily distinguished by scales 

 on the head, and the teeth on the jaws, by the forms and dentition of the pha- 

 ryngeals, the structure of the air bladder, and by their habits. In a general 

 way it may be said of this family they are surface fishes, while the Carps, 

 properly so designated, are fishes of the bottom. All the Cyprinodonts are 

 small ; none of them reach the length of a foot, most are less than six 

 inches ; and among them are found the smallest of the fishes, in species 

 of which the individuals are fully mature at a length of less than an inch. 

 From carnivorous they range to mud-eating, and from oviparous, laying 

 numerous eggs, to ovoviviparous, producing comparatively few. Like other 

 bony fishes some lay their eggs ; others retain the embryo until the yolk 

 is entirely absorbed ; in a few of those that keep the embryo until fully 

 developed, it is provided with albuminous nutriment, in addition to the 

 yolk, within the egg, and is possessed of a peculiar temporary absorption 

 system by which it avails itself of the provision. From ordinary sexual 

 habits, such as most prevail among their allies, the Cj'prinodonts vary to 

 the extraordinary conditions, described below, in which the males and 

 females are rights and lefts, that is, in which a dextral male pairs with 

 a sinistral female, or a sinistral male with a dextral female. In this case 

 sexes exist in nature that in a measure are 



" Like those sweet birds that fly together, 

 With feather always touching feather, 

 Linked by a hook and eye," 



of the poet's imagination.* 



* Trauslated by Moore from Abdallnli's Persian, referring to the jaftak, "a sort of bird that is said to 

 have but one wiug; on the opposite side to which the male has a hook and the female a ring, so that when 

 they fiy they are fastened together." 



