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Rh microscopic longitudinal or concentric riblets and the nature of the apical slits are often useful for identification. Few of our American species, other than a few pinkish or yellowish forms, can boast of colorful shells; but in the East Indies such forms as Dentaliun elephantinum Linné are brightly hued in various shades of emerald green and jade. Some species of Dentalium have a terminal pipe projecting out of the posterior end.

There are only two families in the class Scaphopoda—the Dentaliidae and the Siphonodentaliidae. Both families are well-represented in our waters, the former by numerous species of Dentalium, the latter by members of the genus Cadulus.