PL. 9

NB

a. Summit or nudeus.

c. The inner or columella tip. d. Outer lip. e. Front edge. f. Hinder edge of mouth. b. Margin of mouth or Peristome. n Longitudinal shit. o. Columella g. The hollow aus or umbilicus. h Spire. i. First whorl. k. Body whorl. 1. Suture. m. Muscular impression. p Dissepiment between the whorls.

N. The Parts of the various shells having the same number or letter are similar.

PLATE I

longitudinal or spiral ribs.

Dohum

expanded into

a canal.