144 



lation is hardly visible, and the shell is often of a dull yellowish 

 color, which on the larger volutions becomes gradually of the 

 characteristic color. 



Melania INTEGRA.— ^Subglobose, horn color; volutions rather 

 more than three, rounded, obsoletely wrinkled; spire very short, 

 less than half the length of the aperture : suture rather deeply im- 

 pressed : body whirl large : aperture dilated, ovate, acute above : 

 columella flattened, polished : labrum regularly rounded : base 

 regularly rounded, without any undulations or sinus : umbilicus 

 none : operculum obviously spiral. 



Length, nearly one-fifth of an inch. 



Animal. — Foot longer than wide, rounded behind ; with the ante- 

 rior angles a little excurved : eyes black, conspicuous ; tentacula 

 rather long and slender. 



Inhabits the Ohio river and many of its tributaries. 



This is a very common little shell, abounding more in many 

 situations than any other species, particularly in the vicinity of the 

 Falls of the Ohio. 



It may readily be mistaken for a young shell. 



Melania isogona. — Subglobose, horn color : volutions about 

 four, rounded, obsoletely wrinkled : spire very short, about one- 

 third the length of the aperture : suture profoundly impressed, so 

 as to cause a shoulder on the whirls : aperture much dilated, oval, 

 being as obtusely rounded above as at base : umbilicus linear, dis- 

 tinct : operculum obviously spiral. 



Length, under three-tenths of an inch. Inhabits Bear-grass 

 creek, near Louisville. 



Not very numerous. It is remarkable by the oval form of the 

 much dilated aperture, and by the deeply indented suture. In 

 old specimens, the base is almost acutely angulated. 



Melania trilineata. — Subglobose oval, yellowish, more or 

 less tinged with brown : volutions about four, rounded, somewhat 

 wrinkled : spire short, rathei' more than half the length of the 

 aperture : suture not very deeply impressed : body whirl with three 

 brownish black revolving lines, of which the two inferior ones 

 are somewhat nearest together, the middle one widest, and the 

 superior one placed near the suture and revolving on the spire ; 

 the middle one is concealed on the spire, by the suture : aperture 

 much dilated, ovate, acute above : labium a little flattened : labrum 



