Sea-slugi 



283 



easily overlooked. Johnston's Seca Lemon {D. john- 

 stoni) is another small species, of a creamy white 

 colour, which harmonises with the paler form of 

 Crumb-of-bread Sponge upon which it feeds. There 

 are dark spots on the back which give the impression 

 that they are deep pores like those of the sponge. 



The Hairy Sea Lemon (Acanthodoris lyilosa) varies 

 in colour from pure white through yellow and brown 

 to grey and even black. It is covered with soft, 



Hairy Sea Lemon (enlarged three diameters) 



conical points which give it a pilose character, and 

 make it very sponge-like in appearance. It occurs 

 between tide-marks, but its habits have not yet been 

 satisfactorily made out; though the very sponge- 

 like texture of the surface leads one to expect that it 

 will be found to feed on several of the encrusting 

 sponges. A second species {A, siihquadrata) is 

 pale and semi-transparent, very squarish at either 

 extremity. 



The Rouo;h Doris (Lamellidoris aspera) is less than 



