Marvels of the Universe 



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Slug specialists of his day any information that would support the idea ; on the contrary, they gave 

 him reason to believe that their beauty was " probably of no service to these animals." A closer 

 acquaintance with them as living animals rather than as museum" specimens" demonstrates 

 clearly enough that both form and colour have special relation to their mode of life and are of the 

 greatest ser\ice to them as a protection against their natural enemies. 



The Sea-slugs must be sought among the weeds and corallines that cover rocks and stones at 

 extreme low water of spring tides and at lower levels. But they are not creatures that can be 

 discovered at a glance, for thej' harmonize so well with their surroundings that even the largest 

 members of the race may be but a few inches before our eyes and yet be unseen. One of the best 

 known of the British species is familiar in books under the name of Sea Lemon, and it is really a 

 good name, for, alike in form, size and colour, it closely resembles the half of a lemon that has been 

 cut lengthwise. As depicted in natural-history books it is a very conspicuous object ; but when 

 it is engaged — as it commonly is — in feeding upon the similarly-coloured Crumb-of-bread Sponge 

 that encrusts our submerged rocks, it is no longer half-lemon or Sea-slug, but part of the sponge. 

 The low wart-like irregularities of its back then appear to be the pores in the substance of the 

 sponge ; and so the sponge is doubly valuable to it ; for it provides a meal and security from inter- 

 ruption whilst it is enjoying that meal. These encrusting sponges, it should be remarked, give off 

 a strong unpleasant odour, which, in all probability, makes them unacceptable as food to other 

 marine creatures, though not to the Sea Lemon. 



But the Sea Lemon is too plainly dressed a Sea-slug to be taken as a pattern of the family, 

 though there are several near relations that are as little adorned. One of these is only about an 



[/ii/ 7'fieo. Carreraa, 

 SO.ME SEA-SLUGS. 



The Sea-Slug9 here reprcECnted are all enlarged to about twice their natural length. The figure to the left is white with a 

 rosy tinge. The one above it. covered with tubercles, is yellowish: the rosette on the lower portion is the breathing organ. The 

 upper figure to the right, with the long snaky appendages, is coloured red with variations towards orange. Its appearance is much 

 liice that of a Sea-Anemone. 



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