BUSYCON. 



381 



prominent part of each wliorl, behind which it is a1)ruptly flattened ; 

 at the suture is a broad and deep channel, so that the upper whorls 



Fig. 645. 



B. canaliculatum 



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

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



