The Organs of Reproduction 



127 



In others, as the surf -fishes (Embwtocida), they are relatively 

 large and few in number. In the viviparous sharks, which con- 

 stitute 'the majority of the species of living sharks, the young 

 are large at birth and prepared to take care of themselves. 

 The eggs of fishes vary very much in size and form. In 



FIG. 94. Egg of Callorhynchus antarcticus, the Bottle-nosed Chimaera. (After 



Parker and Haswell.) 



those sharks and rays which lay eggs the ova are deposited in 

 a horny egg-case, in color and texture suggesting the kelp in 

 which they are laid. The eggs of the bull-head sharks (Heterodon- 

 tus) are spirally twisted, those of the cat-sharks (Scyliorhinidcz) 

 are quadrate with long filaments at the angles. Those of rays 

 are wheelbarrow-shaped with four "handles." One egg-case 



FIG. 95. Egg of the Hagfish, Myxine limosa Girard, showing threads for attach- 

 ment. (After Dean.) 



of a ray may sometimes contain several eggs and develop 

 several young. The eggs of lancelets are small, but those of 

 the hagfishes are large, ovate, with fibres at each side, each with 

 a triple hook at tip. The chimaera has also large egg-cases, 

 oblong in form. 



In the higher fishes the eggs are spherical, large or small 

 according to the species, and varying in the firmness of their 



