﻿PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  

  

  vol. 
  67 
  

  

  and 
  one-half 
  turns 
  we 
  again 
  have 
  ribs 
  appearing, 
  but 
  these 
  ribs 
  are 
  

   large, 
  broad, 
  rough, 
  and 
  rather 
  ill-defined. 
  Suture 
  moderately 
  

   impressed. 
  Periphery 
  of 
  the 
  last 
  turn, 
  which 
  is 
  rather 
  high, 
  marked 
  

   by 
  a 
  very 
  strong 
  carina 
  with 
  a 
  pinched-in 
  area 
  immediately 
  above 
  

   and 
  below 
  it. 
  The 
  basal 
  wall 
  sloping 
  to 
  the 
  umbilical 
  chink 
  is 
  marked 
  

   by 
  numerous, 
  rough, 
  slightly 
  lamellar 
  ribs. 
  There 
  are 
  here 
  also 
  

   some 
  indications 
  of 
  spiral 
  sculpture. 
  Aperture 
  moderately 
  large, 
  

   more 
  or 
  less 
  triangular, 
  with 
  a 
  broad, 
  expanded 
  and 
  reflected, 
  wide 
  

   peristome 
  which 
  is 
  free. 
  The 
  summit 
  of 
  the 
  free 
  portion 
  of 
  the 
  last 
  

   whorl 
  forms 
  a 
  strong 
  carina. 
  The 
  outside 
  of 
  the 
  free 
  portion 
  of 
  the 
  

   parietal 
  wall 
  is 
  marked 
  by 
  the 
  continuation 
  of 
  the 
  axial 
  ribs. 
  

  

  The 
  type, 
  Cat. 
  No. 
  361964, 
  U.S.N.M., 
  was 
  collected 
  east 
  of 
  Mon- 
  

   clova, 
  Coahuila, 
  Mexico. 
  It 
  has 
  17 
  whorls 
  and 
  measures: 
  Length 
  

   22.1 
  mm.; 
  diameter, 
  5.3 
  mm. 
  

  

  Twenty-four 
  additional 
  specimens, 
  Cat. 
  No. 
  361965, 
  U.S.N.M., 
  

   yield 
  the 
  following 
  measurements 
  : 
  

  

  *Type. 
  

  

  Another 
  lot, 
  Cat. 
  No. 
  361966, 
  U.S.N.M., 
  taken 
  at 
  an 
  altitude 
  of 
  

   3,000 
  feet, 
  about 
  halfway 
  between 
  Nueva 
  Leon 
  and 
  Monclova, 
  

   Coahuila, 
  Mexico, 
  appears 
  to 
  belong 
  to 
  this 
  species. 
  Twenty-four 
  

   specimens 
  of 
  this 
  lot 
  yield 
  the 
  following 
  measurements: 
  

  

  