86 STATES OF INSECTS. 



many interesting particulars 3 . I must not conclude tins 

 subject without observing, that the female Pycnogonida, 

 an osculant tribe between Insects and Crustacea, carry 

 their eggs upon two pair of false legs b . 



iii. Substance. From this long dissertation on the situ- 

 ation of the eggs of insects and matters connected with it, 

 I pass on to their substance or their external and internal 

 composition, giving at the same time some account of the 

 embryo included in them. The eggs of insects, like those 

 of birds, consist in the first place of an external coat or 

 shell, varying greatly, as to substance, in different genera. 

 Most commonly, particularly in those which deposit their 

 eggs in moist situations, as in dung, earth, and the like, 

 it is a mere membrane, often thin and transparent, and 

 showing, as in spiders, all the changes that take place in 

 the inclosed embryo, as the formation of the head, trunk, 

 and limbs c . This membrane is sometimes so delicate 

 as to yield to the slightest pressure, and insufficient to 

 protect the included fluids from too rapid an evaporation, 

 if the eggs be exposed to the full action of the atmosphere. 

 In most Lepidoptera, and several other tribes, this inte- 

 gument is considerably stronger, in those moths whose 

 eggs are exposed throughout the winter, as Lasiocampa 

 Neustria, &c, so hard as not to yield easily to the knife. 

 Even in these, however, its substance is more analogous 

 to horn or a stiff membrane than to the shell of the eo-o-s 

 of birds. Nothing calcareous enters into its composition, 

 and it is not perceptibly acted upon by diluted sulphuric 



a Vol. I. 349-. 371—. " .V. Diet. d'Hist. Nat. xxviii. 271. 



e De Geer vii. 194, 



