57 
enclosing substance being so tough as to require the employ- 
ment of a cutting instrument to ilivido 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 bottom to obtain 
its full developemcnt 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 stale, 
except that the tail is employed in causing the splashing sound 
beard by fishermen in a still evening, when none are found to 
onter the net. 
A greater degree of heat, more uniform and congenial than 
any afforded by mere shelter, is sometimes required, and the 
body of tlie parent is mude the procreant cradle of the oil- 
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 
a ny one class or order; for whilst only one known species of 
iMenny (Blennius Viviparus) is viviparous, some of the Sharks 
ar e exceptions in an opposite mariner, to the general habit of 
their race ; their eggs being enclosed in purses of curious con- 
duction, that guard them from the actual presence of the 
®alt water. That the oviparous or viviparous manner of hatch- 
jig lias close relation with the power of the egg to develope 
beat 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. <J14) that some 
.'pung animals, as puppies and kittens, but especially such 
llr ds as are delivered from the egg in a naked condition, a 
Ca se more in point since, being oviparous, they approach more 
•‘early to the nature of fishes, require so small a quantity of 
° x Jgen or vital air for the purpose of supporting life, that 
'hey may be deprived of that gas altogether for twenty mi- 
nutes without material injury; but then it is necessary that 
'hey should derive an artificial heat from the mother, because 
•heir own vital action is not sufficient to support their proper 
j'liipeiature : whereas such birds as are well feathered when 
. le y quit the egg, are able to support their own temperature, 
“t require a good and constant supply of oxygen. VVc know 
hke manner, that the eggs of oviparous fishes, though often 
eposited at a cold season, are so placed as to obtain the most 
Abundant supply of vital air ; but the egg hatched within the 
° l 'y, almost entirely cut oil' from that of which it has little 
eed, has the requisite warmth supplied from the mother. 
a some cases indeed, both these objects are joined in one, 
' s m the Snake Pipefish, (Syngnathus Ophidion) where the 
