60 LAND AND FRESH-WATER SHELLS OF N. A. [PART I. 



seaboard are infested with several European species, introduced 

 by commerce. Like rats and mice, and various destructive 

 insects which have proceeded from continent to continent and 

 from island to island in the same manner, they occupy the houses 

 and other structures, in the immediate vicinity of man, preying 

 upon the fruits of his industry, and consuming his stores of pro- 

 visions. Like them they thrive only in the vicinity of, and, as it 

 were, in contact with man, and never withdraw from him to re- 

 sume their original manner of living in the wilds. These habits 

 are the cause of much mischief, and when the animals are numer- 

 ous, I'cnder them the pests of the house and the garden. Their 

 increase therefore, beyond a certain point, becomes prejudicial, 

 and means are adopted to keep them in check. In various ways 

 thousands of them are destroyed during the year, but their ex- 

 traordinary fertility enables them to make the loss good and to 

 sustain themselves in undiminished numbers. 



Species of the genus found in this country can be readily con- 

 founded only with those of the genus Avion. They can be at 

 once distinguished by their smooth jaw with its rostriform pro- 

 jection, that of Avion being ribbed and regularly concave ; the 

 respiratory orifice of Limax is on the hinder part of the shield, 

 while in Avion it is on the anterior portion ; the rudimentary shell 

 of Limax is strong, oblong or square, while in Avion there are 

 but irregular grains of calcareous matter. 



There exists no confusion regarding the nomenclature and 

 synonymy of Liviax, though species have formerly been described 

 under a variety of names. 



The characteristics of the shield furnish points on which to 

 base a division of the species into two subgenera — Amalia and 

 Eulimax. In the former it has more or less prominent wrinkles, 

 while in the latter it is regularly and concentrically striate. 



I 



Subgenus AMALIA. 



Shield more or less apparently rugose, without concentric 

 striae. 



Spurious Species of Amalia. 



Limax columbianus, Gould, is the same as Ariolimax columbianus, Gould, ■ 

 q. V. 



