GASTROPODS. 



343 



shaped, and are generally laid in the earth under stones or leaves, and there left 

 to hatch by themselves. On emerging from the egg, the animals are practically the 

 same as the parent, but the form of the shell, when present, generally alters very 

 much in the course of growth. 



Shelled Slugs, — Family Testacellid^ 



The shelled slugs, or Testacellidw, have no jaws, but are armed with a tongue 

 bearing oblique series of long, narrow, pointed teeth, indicative of their carnivorous 

 habits. While some members of the family are without any external shell, the 

 majority are provided with shells capable of entirely covering the animals, but a 

 few have only very small ear-shaped shells attached to the upper surface of the 

 hinder end of the foot. To the latter group belongs Testacella, the typical form 

 of the family. This genus includes elongated slug-like animals, with the breathing 

 orifice at the posterior end of the body, which is capable of great extension and 

 contraction. They prey upon earthworms, which are pursued in their burrows under 

 ground. In a recent account of the habits of T. scutulum, Mr. Webb observes that 

 it usually seized the anterior 

 end of the worm, and gradu- 

 ally swallowed it ; but occa- 

 sionally the middle was 

 seized, in which case the 

 worm forced itself away. 

 During cold northerly and 

 easterly winds these crea- 

 tures enclose their bodies in 

 a kind of cocoon, like that 

 of the silk-worms, which is 

 secreted from the skin, and 

 often mixed with earthy and 

 extraneous particles. These slugs deposit a few calcareous eggs, which in form 

 are as symmetrical as those of a bird, and large in proportion to the size of the 

 animal. It is doubtful whether this genus is truly indigenous to Great Britain, 

 or merely an introduction of comparatively modern times. The only other parts 

 of the world besides Europe where Testacella occurs, are Algeria and the Azores, 

 Madeira, and Canary Islands. 



Glandina forms an extensive genus of Testacellidw, chiefly restricted to the 

 central parts of America ; one species, however, being European. Like Testacella, 

 these are very voracious, and even attack their own species. Daudebardia is another 

 slug-like genus of this family, carrying a small shell upon the tail. They occur 

 in Southern and Eastern Europe and Western Asia, and in New Zealand are closely 

 represented by Schizoglossa, the external aspect of which is very similar. The 

 allied Streptaxis is remarkable for the peculiar obliquity of the last or body-whorl 

 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 



shell-bearing slug, Testacella haliotidea (nat. size 



