BUSYCON. 



381 



prominent part of each whorl, behind which it is a])ruptly flattened ; 

 at the suture is a broad and deep channel, so that the upi)er whorls 



Fig. 645. 



-B. eanaliculatum 



are composed of an upright portion, and a nearly horizontal one, 

 all terminating in a pointed apex, and forming a winding terrace 



