272 LAND AND FRESH- WATER SHELLS OF N. A. [PART t 



Chimotrema planiuscula, Raf. Stenotrema convexa, Raf. 



Hemiloma avara, Raf. Toxostoma globularis, Raf. 



Mesodon maculata, Raf. Toxolrema globularis, Raf. 



Mesomphix, Raf. Toxotrema complanata, Raf. 



Odomphium, Raf. Triodopsis lunula, Raf. 



Odotropis, Raf. Trophodon, Raf. 



Omphalina, Raf. ^Cjplotrema lunula, Raf. 



Omphalina cuprea, Raf. Xolotrema triodopsis, Raf. 

 Stenostoma convexa, Raf. 



Oxyurus quadrilus, Raf., is a typographical error of my own in my 



" Notes," No. 4. No such name was proposed by him. 



Family ARIONID^. 



Lingual membrane with numerous similar, transverse 

 rows of teeth. 



Jaw smooth with a central projection, or ribbed and hav- 

 ing no central projection. 



Body elongate, attached its whole length to the upper 

 surface of the foot, or more or less spiral and prominent on 

 the middle of the upper surface of the foot. Eyes at the 

 end of long, cylindrical, retractile peduncles ; tentacles 

 shorter, retractile. Mantle thin, small, discal or spiral, on 

 the middle of the back, respiratory orifice subcentral, on the 

 right side. Foot narrow, elongate, usually with a distinct 

 locomotive disk, with a posterior, distinct gland. Vent near 

 the respiratory orifice. Orifice of reproductive organs usu- 

 ally behind the right peduncle, or below the respiratory 

 orifice. 



Shell thin, shining; peritreme acute, simplo or sometimes 

 internal and rudimentary. 



This family contains numerous genera and species found in 

 every quarter of the globe. In North America it is represented 

 by only two genera, Arion and Zonites. Their habits are re- 

 spectively the same as those of Limax and Hyalina. 



The shell exists in various stages of development in the 

 Arionidse, in some containing a portion of the animal in spiral, 

 in others being internal, and the body attached to the foot in its 

 whole length. This and the characteristics of the mucous pore 

 have suggested the two subfamilies Arioninse and Zonitinae. 



