APLYSIA. DOLABELLA. 65 



racters, having little resemblance except in their 

 gibbous form. Bulla naucum is an example of 

 the genus of Lamarck's system ; so is B. lignaria. 

 (See Frontispiece.) B. ampulla and B. striata 

 are common in collections. 



" Aplyslana is a small family, containing 



Aplysla^ or Sea-hare. 

 Dolahella. 



" One species of Apt y si a is found on the De- 

 vonshire coast : the name Sea-hare marks the 

 singularity of the two tentacula, which resemble 

 the ears of the hare. The body is folded up in a 

 loose skin, or mantle : upon the middle of the 

 back it carries a circular shield, thin, transparent, 

 and yellowish, in which it resembles the slug. 

 These animals swim with ease. 



*^ Dolahella resembles the Aplysia in some 

 degree ; the genus is foreign, and one species 

 is known to inhabit the bays of the Isle of 

 France, where it covers itself with a portion of 

 mud." 



" I cannot understand why animals related 

 to the slugs should find a place here," said 

 Charles. 



" Have not slugs the characteristics of the 

 Mollusca class ?" asked his father. " And are 

 you quite sure that they are without a shell ^ 



