LIMAX. 141 



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 in- 

 dustry, and consuming his stores of provisions. Like them they thrive only in 

 the vicinity of, and, as it were, in contact with man, and never withdraw from 

 him to resume their original manner of living in the wilds. These habits are 

 the cause of much mischief, and when the animals are numerous, render 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 extraordinary 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 confounded only 

 with those of the genus Arion. They can be at once distinguished by their 

 smooth jaw with its rostriform projection, that of Arion being ribbed and regu- 

 larly concave below ; the respiratory orifice of Limax is on the hinder part of 

 the shield, while in Arion it is on the anterior portion; the rudimentary shell 

 of Limax is strong, oblong or square, while in Arion there are but irregular 

 grains of calcareous matter. 



It will be noticed that the genitalia furnish reliable specific characters in the 

 Limaces found within our limits. The variation shown in the shell of the he- 

 liciform genera seems here to be transferred to these organs. It seems to be a 

 generic character that the testicle is composed of aciniform caeca, and is not 

 imbedded within one of the lobes of the liver. 



As some confusion exists in regard to the specimens furnishing the descrip- 

 tions and figures of dentition published in this country, I have taken pains to 

 be sure of the specific identity of each specimen from which my own are 

 drawn. 



The L. maximus was collected in Newport, R. I., by my friend, Mr. 

 Samuel Towel. It is the same individual figured on p. 408 of my edition of 

 Gould's " Invertebrata of Massachusetts." The external markings of the ani- 

 mal are conclusive proofs of its identity with the European species. 1 have, 

 however, made it still more certain by examining the genitalia, which I find 

 agree with those of L. maximum, figured by Lehmann (Lebenden Schnecken, 

 etc.). I find the dentition agrees also with the figures given by Heynemann 

 (Malak. Blatt. X.), Lehmann (1. c), and Goldfuss (Verhl. Naturh. Vereins der 

 Preuss. Rheinl., etc.). 



The L. Jlavus was collected in a cellar in Burlington, N. J. It not only 

 agrees with the figure in the "Terrestrial Mollusks" as far as its outward 

 markings are concerned, but I find also its genitalia to agree with Dr. Leidy's 

 figure in the same work, and also with the figure given by Moquin-Tandon 

 (Moll. Fr.). Its dentition agrees with the figures of Heynemann and Semper 

 (Arch. Phil.)- 



The L. agrestis was collected in a garden in Burlington, N. J. This spe- 



