TRUE SLUGS 



3313 



in relation to the spire in most of the species. The first-formed part of the shell is 

 regular in its growth, like an ordinary garden snail shell, but suddenly the growth 

 becomes irregular, giving the shells a very oblique and distorted appearance. The 

 object of this deviation from the ordinary form of growth is not apparent, but it 

 doubtless serves some special purpose. Nearly all the species of this genus are 

 of a whitish color, polished or obliquely striated. They chiefly occur in South 

 America, tropical Africa, Southern Asia, and certain islands in the Indian Ocean. 



TRUE SLUGS Family 



This family contains many genera of naked slugs, and several either partly or 

 wholly protected by well-developed shells; the hinder end of the foot in some forms 

 terminating in a conspicuous mucus or slime pore. The typical slugs are mostly 

 elongate animals, capable of great contraction, and always pointed or attenuated be- 

 hind. The mantle forms a sort of shield, placed over the fore part of the back, and 

 beneath this is situated a small calcareous plate, representing the shell. These 

 plates occur fossil in Eocene beds. The respiratory orifice is seen on the right side 

 of the shield, but rather far back. The head is prominent in front, bearing two 

 pairs of retractile tentacles, of which the upper are the longest, and furnished with 

 eyes at the bulbous tips. The mouth is provided with a horny upper jaw, which is 

 smooth, with the cutting edge produced into a sort of beak in the middle. The 

 radula has numerous transverse series of horizontal or slightly oblique teeth, of 

 which the central tooth is three pronged, the laterals about the same height as the 

 central one, while the marginal teeth are narrow and acute. The body is united to 

 the foot, and is more or less wrinkled; the wrinkles being most conspicuous when 

 the slug is contracted, and to some extent characteristic of the different species. 

 The Limacida live in damp places, out of doors, or in cellars, and hide away during 

 the daytime under stones, dead leaves, or in fact in any place where it is dark and 

 moist. They feed chiefly on decaying vegetation, but some are more or less carniv- 

 orous. Certain species are great pests in gardens. Limax agrestis, the ' ' milky 

 slug," so called from the opaque white color of its mucus, as a very common 

 species in England; it is very fond of strawberries, and is also said to feed upon 

 earthworms. These slugs increase in numbers rapidly, and are said to produce 

 several families in the course of a summer; a pair having been known to lay nearly 

 eight hundred eggs. Some species of Limax are capable of lowering themselves to 



the ground from the branch of a 

 tree by secreting a slimy thread. 

 The largest species occurring in 

 Britain is L. maximus, which 

 has a very wide range on the 

 Continent, and sometimes ex- 

 ceeds six inches in length. One 



GI.ASS-SNAII. ( Vitrina) AND AMBER-SNAII, (Succinea). ma > r often notice numbers of a 

 (Natural size.) minute white parasitic mite 



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