57 



enclosing substance being so tough as to require the employ- 

 ment of a cutting instrument to divide it ; but at the end of a 

 few days, decomposition took place, and the pea having passed 

 through a part of its change, dropped to the hottoni to obtain 

 its full developement in a place of greater safety. Mr. Jesse 

 reports the Shad to shed its spawn by night at the surface 

 of the river, using the action of its tail to assist its efforts; 

 the Pilchard, a kindred species, probably acts in a similar 

 manner, being sometimes seen to lie on the surface extended 

 on its side, multitudes together being in a quiescent stair, 

 except that the tail is employed in causing the splashing sound 

 heard by fishermen in a still evening, when none are found to 

 enter the net. 



A greater degree of heat, more uniform and congenial than 

 any afforded by mere shelter, is sometimes required, and the 

 body of the parent is made the procreant cradle of the off- 

 spring: — in a manner however, even here, no less diversified 

 than in other portions of the Almighty's works. 



Fishes that produce their young alive are not confined to 

 any one class or order ; for whilst only one known species of 

 Blenny (Blennius Viviparus) is viviparous, some of the Sharks 

 are exceptions in an opposite mariner, to the general habit of 

 their race; their egi;s being enclosed in purses of curious con- 

 struction, that guard them from the actual presence of the 

 salt water. That the oviparous or viviparous manner of hatch- 

 ing has close relation with the power of the egg to develope 

 heat for its own use, or to exist, on a smaller portion, is ren- 

 dered probable by the following considerations: The late 

 Professor Turner informs us (Chemistry, p. 914) that some 

 young animals, as puppies and kittens, but especially such 

 birds as are delivered from the egg in a naked condition, a 

 case more in point since, being oviparous, they approach more 

 nearly to the nature of fishes, require so small a quantity of 

 oxygen or vital air for the purpose of supporting life, that 

 they may be deprived of that gas altogether for twenty mi- 

 nutes without material injury; but then it is necessary that 

 they should derive an artificial heat from the mother, because 

 their own vital action is not sufficient to support their proper 

 temperature : whereas such birds as are well feathered when 

 Ihey quit the egg, are able to support their own temperature, 

 but require a good and constant supply of oxygen. We know 

 in like manner, that the eggs of oviparous fishes, though often 

 deposited at a cold season, are so placed as to obtain the most 

 abundant supply of vital air; but the e»g hatched within the 

 body, almost entirely cut off from that of which it has little 

 need, has the requisite warmth supplied from the mother. 

 Iu some cases indeed, both these objects are joined in one, 

 as in the Snake Pipefish, (Syngnathus Ophidion) where the 



