1 66 ANIMAL BIOLOGY 



is capable of inflicting a painful wound. The torpedo 

 which is allied to the rays is remarkable in possessing a 

 highly developed electric organ which may give rise to 

 very severe electric shocks. 



Most of the elasmobranchs lay large, yolk-laden eggs 

 which are fertilized before they are laid. In many cases 

 these hatch within the body of the mother so that the 

 young are brought forth alive, but in some forms the eggs 

 are enclosed in a horny shell, which is sometimes drawn 



FIG. 134. Lepomis punctatus. Chinquapin perch. 



out at the two ends into four cords by means of which 

 they become attached to sea-weeds. 



The Teleostomi include the fishes with a more or less 

 bony skeleton. The gill-slits are covered by an opercu- 

 lum and the body is generally covered with flattened scales. 

 The most primitive of these are the ganoids which in 

 early periods of the earth's history constituted a large 

 and flourishing group. Now they are represented by a 

 comparatively few forms, a large proportion of which are 

 found in the fresh waters of North America. The large 

 sturgeon of our lakes and rivers whose ovaries are sold 

 as caviar; the slender, hard scaled gar pike; and the dog 



