254 LIFE BY THE SEASHORE. 



existence of a free-swimming stage in Doris must facilitate 

 distribution. It is possible that the young may travel 

 distances impossible to the sluggish adults. 



To return to the special characters of Doris bilamellata. 

 The body is about an inch in length and is greyish speckled 

 with brown; the back is covered with numerous large 

 unequal tubercles, and there are numerous simply pinnate 

 gills. 



A prettier species is D. pilosa, which is also very com- 

 mon in the Firth of Forth, and is about the same size 

 as the preceding species. It is easily distinguished by its 

 markedly convex shape, and the dense covering of slender 

 soft papillae on the back, which give it a "pilose" appear- 

 ance. The colour is usually white, but is occasionally 

 brown or even black. There are from seven to nine large 

 gills which are not retractile, and the oral tentacles are 

 broad and flat. 



All these species are more or less common on the East 

 Coast, and I have named them all because they are readily 

 distinguished, and are worth careful study. There are a 

 great number of other species, mostly rare or absent on the 

 East, but in the Firth of Forth all those mentioned can be 

 found without difficulty. They all occur also around the 

 coast generally. 



While hunting for species of Doris, you are almost certain 

 to find an animal very like a Doris in appearance, but of 

 somewhat different shape, and of delicate pinkish colour. 

 The body is smooth, oblong, and elongated, the foot project- 

 ing markedly behind the cloak when the animal creeps. The 

 cloak is almost a quadrilateral, and has a distinct keel down 

 the centre. Its margin is reflected and indented posteriorly. 

 There are thirteen simply pinnate gills which are not re- 

 tractile. This is Goniodoris nodosa (see Fig. 73), a most 

 graceful little creature, usually pink, speckled with white, 

 but sometimes white or yellow. It reaches a length of 

 about an inch, and is abundant everywhere under stones. 

 The breeding season is in March (in the Firth of Forth), 

 when the animals congregate in large numbers, and lay 

 ropes of spawn, very different in shape from the frilled 

 ribbons of Doris. This species lives fairly well in con- 

 finement, and is a great addition to an aquarium, where its 



