222 POPULAR BRITISH CONCHOLOGY. 



that we read of in books^ even if pictured in true colours on 

 the plates^ as by those which we can see and feel. 



Graphic as are the descriptions, and exquisitely true as 

 are the pictorial representations, of the Nudibranchiate 

 Mollusca published by Messrs. Alder and Hancock, that 

 work will perhaps be less read, except by thorough natu- 

 rahsts, than very inferior productions, referring perhaps 

 to mere shells. For this reason, we must be content with 

 passing lightly in review before us some of the British re- 

 presentatives of this order. Let, then, a few of these sea- 

 slugs crawl before us in procession. 



First comes the Doris tribe, represented in our seas by a 

 long train of seventeen species. We choose for description 

 one of the prettiest, Boris planata. Creeping along, with its 

 mantle fully expanded, it presents to the eye an oblong, oval, 

 flattened, fawn-coloured disc, covered with small tubercles, 

 and prettily sprinkled with light spots and brown specks : 

 towards the hinder end of this disc is seen the vent, around 

 which is arranged a branched star — this is the breathing 

 organ ; towards the front end there are two holes, through 

 which are thrust two tentacles, thickened in the middle and 

 ornamented with coiled ridges. With the exception of the 

 protruding end of the foot, this is all we see until the animal 



