534 



PISCES FISHES. 



division of this extensive class. The earth is peopled only at its 

 surface, and the vegetable banquet there spread is abundantly suffi- 

 cient for the support of terrestrial beings. The ocean, however, 

 being densely populated at every assignable depth, could never 

 have supplied vegetable food to anything like the extent required 

 to satisfy her progeny ; hence, therefore, the necessity for that 

 astonishing fertility so remarkable in the osseous fishes nine mil- 

 lions of ova have been calculated to be spawned at a birth by a 

 single cod-fish : such spawn, being naked and unprotected, is 

 eagerly devoured by thousands of hungry mouths, or the feeble 

 young soon fall a prey to countless voracious persecutors. If, how- 

 ever, it was obviously requisite that the progeny of osseous fishes 

 should be thus multitudinous, in order to provide a sufficiency of 

 needful food, it is equally clear that it would have been incom- 

 patible with the design of the Creator that the ravenous Sharks 

 should be endowed with equal fecundity : their eggs are conse- 

 quently few in number ; and, in proportion to their scarcity, jealous 

 precaution must be taken to insure the safety of the included 

 young, in order to prevent the complete extinction of the race. 



The means employed for this Fig. 236. 



end are simple and beautiful. 

 About the middle of the ovi- 

 duct of the female there is a 

 thick glandular mass, destined to 

 secrete a horny shell in which the 

 yolk and white of the egg be- 

 come encased. The egg when 

 complete has somewhat the 

 shape of a pillow-case, with the 

 four corners lengthened out 

 into long tendril-like cords 

 (fig. 236), whereby the egg is 

 entangled amongst the sea-weed 

 at the bottom of the ocean. A 

 brittle egg-shell would soon be 

 destroyed by the beating of the 

 waves, hence the necessity for 

 the corneous nature of the envelope ; and yet how is the feeble 

 embryo to escape from such a tough and leather-like cradle ? This 

 likewise has been provided for: the egg remains permanently open 

 at one extremity, or, to carry out our humble simile, one end of 

 the pillow-case is left unsewn ; the slightest pressure from within, 



