The Naked Sea Slugs 



colouring serves as a danger signal, then, to all sophisticated 

 enemies. 



When the /^olis is full grown it is four inches long. The 

 eggs are laid in a gelatinous cord coiled on rock faces or looped, 

 festoon-like, on seaweeds. The young have glossy shells, coiled 

 like that of the chambered Nautilus, which are soon absorbed. 

 The rasping tongue has but one central row of teeth. 



The Bushy-backed Slug {Dendronotus arborescens, Miill.) 

 is covered with a forest of miniature tree forms, the elaborately 

 branched cerata, which disguises the creature as it hides among 

 branching corallines and seaweeds whose rosy or brown marbled 

 colouring it imitates faithfully. This is a distinctly edible slug, 

 from the view point of a fish; therefore protective coloration 

 is its only defence. The adult is a little over an inch in length. 

 No wonder it shrinks from exposure in the clear water where it 

 would be conspicuous. 



This is a very desirable addition to a marine aquarium jar. 

 Put in a few pebbles with their tufts of bright coralline, and 

 some ruddy algae with their animated molluscan imitator. It is 

 a marvellously interesting and beautiful study, but you must 

 have a stick to poke up the shy creature. 



The grove on its back serves the slug for gills. At the base 

 of each tree is a pouch, a stomach annex, supplied with branches 

 of the liver; here digestion proceeds. The New England coast 

 and opposite, across the Atlantic, is inhabited by this mollusk. 



The Sea Lemon or Warty Slug (Doris tuherculata, Linn.) 

 somewhat resembles half a lemon, cut in two lengthwise. The 

 yellowish back is warty and stiffened by limy spicules ; there are 

 gill plumes arranged in a rosette on the posterior end of the back; 

 two leaf-like tentacles rise in front. The creature glides slowly 

 on its flat foot, concealed by its resemblance to the crumb-of- 

 bread sponges, which are its principal food. 



The egg ribbon is wound into a remarkable rosette form, 

 and glued to a rock. Each contains many thousand eggs. The 

 young ones have nautiloid shells. The adults are rarely over 

 three inches long. 



D. bilamellata, Linn., is the common New England species. 

 D. tuberculata, Linn., of Great Britain, is nearly as broad as 

 long. 



D. Montereyensis, Coop., of the California coast, is yellow- 



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