164 REPRODUCTIVE ORGANS. CHAP. III. 



is winged. Its substance is succulent, as in. the 

 Plum ; or fibrous, as in the Cocoa-nut; or dry and 

 leathery, as in the Almond, Sparganium, and 

 Gaura, which last are nearly allied to nuts. It 

 opens for the most part merely by accident or 

 decay ; but in the Peach and perhaps a few others, 

 it opens spontaneously. 



The shell. The shell of the drupe is generally very hard, 

 whence the appellation of stone fruit. But in 

 some cases it is crustaceous and tender, as in 

 Styrax callophyllum; in some it is leathery, as in 

 Hyph&ne ; and in some woody, as in Cerbera* 

 It does not perhaps in any case open spontaneously, 

 and yet there are some shells in which the traces 

 of valves may be discovered, as in that of Elceo- 

 carpus ; or in which a division may easily be ef- 

 fected by means of the knife, as in Prunus. In- 

 complete valves, indeed, are sometimes found at 

 the top of the shell, as in Nitraria and Gaura, so 

 as to make it resemble a toothed capsule ;-{~ and in 

 a few genera there is an opening formed by means 

 of a hole or pore at the top, as in the Cocoa-nut. 



The figure of the shell is very often elliptical, or 

 egg-shaped, but compressed, assuming however a 

 * great variety of modifications, sufficient in most 

 cases to determine the species. Its surface is never 

 quite smooth, but often rough and irregularly fur- 

 rowed, as in the Peach ; in order perhaps that it 



* Gxrt. De Sem. Introd, t Ibid. 



