8^ OF CARTILAGINOUS FISHES. 



dy of the female ; this egg confifts of two parts, the 

 white and red, as in thofe of birds, and inftead of a fnell, 

 it is lodged in a cafe formed of a thick toDgh fubllance, 

 refembling a horn that has been foftened in boiling wa- 

 ter *. 



The oviparous fifhes of this clafs produce their young 

 ncr.rlj in the fame manner ; in thefe as well as in the vivipa- 

 rons kinds, the egg is hatched for fome time in the belly 

 of the female, but before the fetus is difengaged from it, 

 is excluded from the womb, and left till time and the 

 W'armth of the fun bring the inclofed offspring to matu- 

 rity. Both diifcr remarkably from the whales and the 

 quadrupeds, whofe eggs ftart from the ovarium, and enter 

 the uterus at the time of conception, where they remain 

 only a few days, till they leave that ftate, and are formed 

 into a complete f"cetu'j. 



There are other difcriminating charaflers belonging to 

 this order, lefs difcernible indeed, but fuch as mark a 

 difference between them and the adjoining tribes. The 

 fpinous fifhes we faw had no aparatus for hearing j it 

 is probable, liovv'cver, that the cartilaginous are furnifh- 

 cd, though imperfectly, with the organs of this fenfe ; 

 upon rach iide, near the eyes, there is an aperture which 

 opens into the mouth, the fupp&led ufe of which is part" 

 Jy to convey the water into the mouth, wliich is expel- 

 led through the gills, and partly to convey founds to the 

 Cenforiumf. In this refpeil, therefore, the cartilaginous 

 fifhes may be deemed a more accomplifhed race than ma« 

 ny of their companions cf the deep. 



The 



* Brilifli Zool. ubl fuyrs. f Will. Icthycl. Lib lil. p. 45- 



