Objects for the Microscope. 163 



PALATE OF PLEUROBRANCH. 



The Pleurobranch is a lemon-coloured, oval-shaped mol- 

 lusc, found under stones in tide-pools, and breathing by a 

 beautiful branchial plume, which is thrown out on the right 

 side, as it glides along, and protected, when at rest, by a 

 thin shell inside the mantle. This palate is quite unlike 

 any of the others, more resembling a tesselated pavement, 

 with a single tooth in each lozenge-shaped division. 



PALATE OF APLTSIA. 



Aplysia is a sea-slug, found in deep rock-pools gliding 

 about with a thick hump-backed body, olive-brown, and 

 tentacles like ears, causing it to resemble a hare. If 

 handled or frightened, it jerks forth a deep purple liquid, 

 which stains the hand or discolours the water. This is 

 evidently its defence, and conceals it from the pursuit of 

 ravenous crustaceans. It belongs to the family of the 

 Pleurobranchs, which have their breathing organs con- 

 cealed within the mantle, but always on the right side, and 

 the palate is broad and short, resembling that of the garden 

 snail, only very much larger. 



PALATE OF DORIS. 

 (Tuberculata.) 



Another variety of sea-slug, much more beautiful, and 

 the palate curiously set with strong hooked teeth like a 

 harrow ; it has forty-four rows, each with 140 of these 

 curved teeth, used for rasping sea- weed. There are many 

 species of Doris usually found under stones at low tide, or 

 beneath tufts of sea-weed ; they are orange-coloured, or 

 pale-yellow, and vary in size from our largest garden slug 

 to a very small one ; on their backs they carry a plume of 

 branchial organs, and are therefore called Nudibranchs, or 

 naked-gilled animals. 



PALATE OF LIMPET. 



Who does not know the Limpet, clinging to the wave- 

 beaten rock, and seemingly as motionless as its native cliff? 



