40 FEBRUARY. 



tiny leaves cut like the fronds of a fern, which stand 

 up over the orifice, and are endowed with the power of 

 absorbing for the purposes of respiration the oxygen of 

 the air commingled in the water. 



But here is an animal which possesses all these pecu- 

 liarities of structure, displayed on a much larger scale. 

 It is a fine specimen of the Sea Lemon, 1 which we 

 oftener find clinging to the sides of perpendicular rocks, 

 or beneath projecting ledges, than on the undersides of 

 stones. This fellow is two and a half inches long, and 

 an inch and a quarter or more broad ; but I have met 

 with individuals much larger than he. Its back is 

 rounded, and its outline generally reminds one of the 

 half of a lemon cut longitudinally. The resemblance is 

 heightened, too, by the round warts with which the whole 

 surface is studded, and by the colour, a yellow more or 

 less pure, often, however, clouded, as in this instance, 

 with purple, by which its beauty is much enhanced. 



The mantle, in this Doris, reaches down to the foot 

 on all sides, and covers the head, and is not furnished 

 with any appendages. The tentacles, which are plated, 

 as in the Triope, pierce through the mantle, and are 

 sheathed ; the gill plumes are large and ample feather- 

 like organs, eight in number, forming a complete circle 



1 Doris tuberculata, which the reader will see figured in Plate iv., in the 

 centre of the foreground. 



