Impressed. Marked by a furrow, as the impressed spiral lines on some univalve 



shells. 

 Ineequipartite. When one end of a shell is longer than the other, as the two ends 



in Pisidium. 

 Incrassate. Thickened. 



Incurrent. The siphon in Unio which brings in the food-stuffs. 

 Incurved. Leaned or bent over, as the apex in some snails. 

 Indented. Notched. 



Inequivalve. When one valve is larger than the other. 

 Inflated. Swollen, as some bivalve shells. 

 Inflected. Turned in, as the teeth of some snails. 

 Inhalent. Same as incurrent. 

 Inoperculate. Without an operculum. 

 Intercostate. Between the ribs or ridges. 



Invaginate. One part bending into another, as the tentacles of some land snails. 

 Invertible. Capable of being inverted, or drawn in, ' as the eye-peduncles 



of a land snail. 

 Involute. Rolled inward. 



Keeled. With a more or less sharp projection at the periphery. 

 Labial. Pertaining to the lips, as the labial-palpi in Unio. 

 Lamellated. Covered with scales. 

 Lamelliform. Having the form of scales. 



Laminated. Consisting of plates or scales laid over each other. 

 Lanceolate. Gradually tapering to a point. 

 Lateral. Pertaining to the side. 

 Latticed. (See decussated.) 



Lenticular. Having the shape of a double convex lens, as some bivalves. 

 Lithodesnia. An accessory shell plate near the umbones, in those shells having 



a " cartilage " or resilium, as in Mactra. 

 Littoral. The region bordering the shore. 

 Lobulate. Composed of lobes. 

 Longitudinal. The length of a shell. 



Lunate. Shaped like a half moon, as the aperture in some shells. 

 Maculated. Spotted. 



Malleated. Appearing as though hammered. 

 Manducatory. Relating to the apparatus for masticating food In snails, the 



jaws and radula. 



Maritime. Inhabiting the seashore. 

 Marsupium. A part of an animal used as a pouch to contain the young, as the 



gills of Unio. 



Median. Middle, as the middle tooth on the radula. 

 Mesocene. The middle cusp on the teeth of the radula. 

 Monoecius. Having the sexes united in the same individual. 

 Multificl. Made up of many lobes or projections, as the cusps on some radulse. 



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