SUCCINEA. 449 



Journ. Portl. Soc. i. 29, fig. 7.3 ; pi. 0, fig- 74 (1864) ; Am. Nat. i. 606, fig. 46 (1868). 

 -Tryox, Am. Journ. Conch, ii. 230, pi. 2, fig. 1 (1866). 

 Succinea obliqua, teste Binney, 1. c. 



Shell obliqucly-ovatc, of a greenish color, thin, shining, some- 

 what diaphanous, obsoletely striated ; whorls three, con- 

 vex, the last very large and globose ; spire very short ; 



suture impressed ; aperture large, oval, oblique ; peris- 

 tome thin, acute. Greatest lengtli, sixteen millimetres. 



New England and New York. 



Generally considered a variety of S. obliqua. It is a 

 thinner and more fragile shell, proportionally more ven- 

 tricose in form, with a shorter spire and larger aperture ; it has a 

 decided green color, almost unshaded with yellow, while in S. ob- 

 liqua the amber yellow predominates. 



Family ARIONIDiE. 



Lingual membrane with numerous similar transverse rows of 

 teeth. 



Jaw smooth, with a central projection, or ribbed and having 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, re- 

 tractile peduncles; tentacles shorter, retractile. Mantle thin, small, 

 discal or spiral, on the middle of the back ; respiratory orifice sub- 

 central, 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 usually 

 behind the right peduncle, or below the respiratory orifice. 



Shell thin, shining, peritreme acute, simple or sometimes inter- 

 nal and rudimentary. 



This family contains numerous genera and species found in every 

 quarter of the glo'je. In North America it is represented by only 

 two genera, Arion and Zonitcs. Their habits are respectively the 

 same as those of Limax and Hijalina. 



The shell exists in various stages of development in the ArioniclcB, 

 some containing a portion of the animal in spiral, in others being 

 29 



