Lives of the Other Mollusks 55 



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 Dentaliwn elephantinum Linne 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 Siphono dentaliidae. Both families are well-represented in our waters, 

 the former by numerous species of Dentaliimt, the latter by members of the 

 genus Cadulus. 



Dentaliidae: Shell tusk-shaped, increasing in size regularly with the greatest 

 diameter at the mouth end. Foot conical. Central tooth of radula twice 

 as wide as long. 



Siphonodentaliidae: Shell bulbous near the middle with the mouth end 

 generally contracted. Foot vermiform, capable of expansion into a 

 rosette-like disk at the end. Central tooth of radula almost square. 



