22 



plaits on the surface of the tube undoubtedly indicate 

 the periodical additions at the different removals of the 

 inhabitant. The great length of the last whorl men- 

 tioned by La Marck, must be of very rare occurrence; 

 in the many examples the writer has examined, it sel- 

 dom exceeded a few inches. 



Mrs. Mawe has possessed examples of this shell in 

 its early stage of growth, in which the spaces or cham- 

 bers were not filled up, and merely presented a divi- 

 sion between them. 



Magilus antiquus. 



TUBICINELLA. 



LEPAS TRACHJEFORMIS. 



Woods Conchology, page 3 1 . 

 Tins animal is at present but little known; the struc- 

 ture of its shell, however, clearly indicates that it must 

 become the type of a distinct genus. The shell is uni- 

 valve, in the form of a cylindrical tube somewhat bent, 

 and rather narrower at the base; open at both ends, 

 the upper one closed by an operculum consisting of 

 four smooth trapezoidal valves affixed to its interior 



