40 LIMACID^E. 



This species varies very much in color, and the descrip- 

 tions by different authors being drawn principally from it, 

 differ greatly from each other ; but whatever may be the 

 color, the peculiar character of the furrows and tubercles 

 remains constant. In a state of contraction, the back is 

 arched, the head is entirely withdrawn under the mantle, 

 the glands of the skin are very prominent, making the 

 surface appear rough, the carina is more apparent, and 

 the posterior extremity, being a little turned to one side, 

 appears to be oblique. It is described by some authors 

 as constantly oblique, but the obliquity disappears when 

 the animal is fully extended. When in motion, the head 

 extends considerably beyond the mantle, and there is an 

 interval between its margin, and the base of the superior 

 tentacle, equal to the length of the tentacles. The 

 mantle adheres to the body by its posterior central por- 

 tion, and it is in this part of it that is found imbedded 

 the testaceous rudiment, or shell. This is oval, curved 

 above, very thin and delicate, having a transparent epi- 

 dermis. At its posterior part there is a slight apical 

 prominence, and the appearance of indistinct concentric 

 lines of growth. 



There is no considerable variation in the species except 

 in regard to color, which varies almost infinitely. 



