318 LOM'ER INVERTEBRATES. 



largely on vegetation, although they are not averse to an animal diet. Since they 

 hide themselves during the day, the damage they occasion is usually attributed to birds, 

 and the larvae of insects, but the presence of slugs can usually be recognized by the pres- 

 ence of streaks of glistening slime in the neighborhood. Most of the terrestrial pulmon- 

 ates are able to secrete a mucus froni their body, and in some there are special pores 

 for its emission. In the sings this capacity reaches a great development, and as they 

 crawl along they leave a streak behind them, which, on di-ying, produces the glistening 

 marks referred to. This secretion of mucus is to a certain extent defensive, and 

 when the animals are irritated the amount is greatly increased. This fact gives us a 

 simple method of checking their ravages, which is to sprinkle coal-ashes around the 

 plants which it is desired to protect. The fine grit of the ashes irritates them, and they 

 pour out the mucus to such an extent that they are soon exhausted, and besides, since 

 it rapidly hardens on exposure to the air, they are soon rendered prisonei's. 



This secretion of mucus is used in another way. Slugs frequently climb trees in 

 search of fruit, and when through feeding they take a quicker method of descending 

 than their ordinary snail's pace. The foot pours out a lot of mucus, which is passed 

 along to the posterior end. This mucus is then attached to the limb on which the 

 animal is, and then the slug casts itself loose. Its weight draws the mucus out into a 

 fine thread, and, more being secreted, the slug lets itself down after the fashion of a 

 spider, with this exception ; it has not the power of returning to the point of support. 

 This power of forming a thread has been observed in almost all the American species, 

 at least when young ; but some of the larger forms, when adult, are too heavy to trust 

 their weight to such a slender support. 



We have spoken of their ravages in gardens, but in America they have not yet 

 become such a pest as in Eui'ope. There they are classed along with caterpillars, 

 locusts, and rats, and a war of extermination is waged against them. In olden times the 

 power of the church was invoked against them, but prayers and anathemas failed to 

 cause their extinction, or in fact any appreciable diminution of their numbers. There 

 is another aspect which should not be passed by without mention. Slugs have long 

 been supposed to have medicinal qualities, the rudimentary shell being regarded as 

 especially efficacious. This belief can hardly be regarded as extinct, as Mr. Binney 

 says that " during the year 1863, a syruj) of snails was jirescribed to members of my 

 family, by two regular French physicians in Paris." During the middle ages, when 

 sujjerstition ran riot, of course they were much more highly esteemed. The shell was 

 regarded as an amidet, protecting the wearer against certain diseases and witchcraft, 

 while the liquid obtained by their distillation was used to improve the eomj>lexion. 

 In Europe they are eaten, but in America neither dietetic imr magic qualities have 

 been assigned to these loathsome appearing animals. 



The Limacidie are divisible into three sub-families. In the first, the Tebenophori- 

 nae, the mantle covers the entire back, and no shell is present. Our only species is 

 Tehenophorus carolinensis, a sluggish, inactive form found in the woods, usually under 

 the bark, or in the interior of decaying logs. It varies considerably in color, from 

 nearly white without spots to white with brown blotches or black spots, and to black- 

 ish gray. It reaches a length of about four inches when fully extended, though at 

 such times the head is not projected beyond the mantle. 



In the Arioninse the shell Tnay be present, though concealed by the mantle, or it 

 may be represented by a number of calcareous grains scattered through the corre- 

 sponding portion of the mantle, a condition which recalls the embryonic condition of 



