CONSTRUCTION OF EGG3. 



125 



up in a ring, as is distinctly shown in many of the 

 beautiful and accurate figures of Sepp.* 



n, egg of the privet hawk-moth (Sphlrx Li-nistn) magnified, 

 showing the incloseil embryo. I, the caterpillnr, when grown. 



In the case of tlie eggs of birds, the chick, when 

 fully developed, breaks the shell with its bill, the 

 point of which is then furnished with a hard scale. 

 'Jhis is evidently contrived by providential wisdom tor 

 this very purpose, for it drops off in a lew days after 

 the chick is excluded. It is probable that the larvae 

 of many insects which are furnished with strong man- 

 dibles gnaw their way through the egg-shell; but we 

 know that there are others which, like the spider, 

 rupture their envelope, since the edges appear ragged 

 and irregular. Others, again, seem to have an open- 

 ing provided tor them, in a door, which c nly requires 

 them to push it open. This is the case with the louse 

 (^Pi<l'u'(liis lunnamis), and with the biid-lonse (A''jr- 

 miis), found on the neck feathers of the golden phea- 

 sant. A still more ingenious contrivance was discov- 

 ered by the Rev. R. Sheppard, in the egg of a f eld 

 bug {Pentatoma, Latr.), which is not only furnish- 



* Per ^^'onderen Hods, paxsim. 

 vol.. VI. 11' 



