115. Back smooth between conspicuous lengthwise furrows; mantle with a 



U-shaped groove; an introduced species often found in greenhouses 

 Milax gagates Drap. Greenhouse Slug 

 (Amalia gagates (Drap.) ) 

 Back with fine transverse striae; no U'shaped groove in the mantle 116. 



116. Back keeled behind mantle; mantle granular; western states 



Zacoleus idahoensis Pilsbry Idaho Slug 

 Back keeled only toward tail; mantle with concentric lines; generally 

 distributed ■ — Gray Garden Slugs 117. 



117. Color grayish or brownish; with flat tubercles over the surface, with 



dark lines or furrows separating them; about 1'^ to 2" long 

 Deroceras reticulatum (Miiller) 

 (Agriolimax agrestis (Linn.) ) 

 Color yellowish to dark; with rounded tubercles over the surface, of the 

 same color as the separating furrows; about 1"" long 

 Deroceras laeve (Miiller) 

 (Deroceras gracile Raf.) 

 (Agriolimax campestris (Binney) ) 



118. With an operculum (a permanent structure attached to the body and 



used to close the aperture of the shell) ; lip more or less reflected; with 

 one pair of tentacles with stalked or unstalked eyes at their bases 119. 

 Without an operculum (Species of Helix and related genera may have an 

 epiphragm — a temporary seal for the opening, while the snail is in a 

 resting condition. This epiphragm is a dried and hardened secretion 

 that is not attached to the body.) ; usually with two pairs of tentacles, 

 with eyes at the ends of the larger pair, sometimes with the small, an' 

 terior pair absent (except Carychium exiguum, which has one pair of 

 tentacles, with a pair of eyes at their bases) 124. 



119. Shell narrow, much higher than wide 120. 

 Shell heliciform, little, if any, higher than wide; less than V2''; southern 



states 121. 



120. Shell lengthwise ribbed; lip continuously thickened and reflected 



Truncatella hilahiata Pfeiffer 

 Shell with fine lengthwise and spiral lines; lip slightly reflected 

 Chondropoma dentatum (Say) 



121. Shell with lengthwise striations 122. 

 Shell smooth 123. 



122. Spire scarcely elevated above the body whorl; less than Vg" wide; Florida 



Lucidella tantilla (Pilsbry) 

 Height about equal to width; about V4"; north-central states to N. C. 

 Hendersonia occulta (Say) 



123. Shell slightly wider than high; slightly under I/4"; southeastern and 



south'Central states 



Helicina orhiculata (Say) 

 Shell slightly higher than wide; slightly over %"; Texas 

 Helicina chrysocheila Binney 



128 



