28 



SHELL GALLERY. 



The shell of the Umbrella is shaped very like that useful article 

 of the Chinese pattern. The animal is very large, having its 

 breathing-organs on the right side below the shell. 



Fier. 16. 



v4< 



The Umbrella-shell (Umbrella mediterranea). 

 a, shell 5 b, gills ; c, tentacles ; d, mouth ; e, foot. 



TCase The Nudibranclis or Naked-gilled Mollusks comprise some of 



*- f j the most beautiful and strange forms. They are unprovided with 



shells except in the earliest stages of their existence, when they 



Fig-. 17. 



mmm 



Naked-gilled Mollusk, or Nudibranch (Doto coronata). 

 a, head ; b, foot ; c, gills ; d, tentacle-sheath ; e, tentacle. 



dwell in a minute nautiloid shell, furnished with an operculum, 

 both of which are subsequently cast off. Unfortunately the 

 colours of these beautiful creatures cannot be preserved after death, 

 and therefore a small series of glass models is exhibited, which 

 will give some idea of their great variety in form and colouring. 

 They are found in most parts of the world, chiefly in shallow 



