﻿KISSOA. 
  Panama 
  Shells. 
  403 
  

  

  24Y. 
  Rissoa 
  infrequent. 
  Nov. 
  sp. 
  

  

  Shell 
  very 
  long, 
  ovate 
  conic: 
  white: 
  with, 
  on 
  each 
  whorl, 
  

   sixteen 
  very 
  obtuse 
  slightly 
  elevated 
  indistinct 
  ribs, 
  which 
  are 
  

   separated 
  only 
  by 
  stri.^, 
  and 
  a 
  few 
  microscopic 
  revolving 
  stride 
  : 
  

   apex 
  subacute: 
  spire 
  with 
  the 
  outlines 
  nearly 
  rectihnear: 
  

   whorls 
  seven, 
  contracted 
  above, 
  otherwise 
  convex 
  or 
  subangular 
  

   with 
  a 
  nioderately 
  impressed 
  suture 
  ; 
  last 
  whorl 
  long, 
  subangu- 
  

   lar 
  : 
  aperture 
  oblique, 
  subovate, 
  scarcely 
  effuse 
  : 
  labrum 
  much 
  

   excurved, 
  well 
  thickened 
  : 
  umbilicus 
  wanting. 
  

  

  Mean 
  divergence 
  about 
  23°; 
  length 
  .24 
  inch; 
  breadth 
  .075 
  

   inch 
  ; 
  length 
  of 
  spire 
  .18 
  inch. 
  

  

  Station. 
  — 
  Unknown. 
  

  

  Habitat. 
  — 
  Panama; 
  C. 
  B. 
  A. 
  ! 
  

   1 
  specimen 
  was 
  obtained. 
  

  

  248. 
  Rissoa 
  Janus. 
  Nov. 
  sp. 
  

  

  Shell 
  long, 
  ovate 
  conic 
  : 
  white 
  : 
  anteriorly 
  with 
  fine 
  crowded 
  

   spiral 
  strige 
  ; 
  elsewhere 
  covered 
  with 
  small 
  crowded 
  transverse 
  

   ribs, 
  which 
  on 
  the 
  last 
  whorl 
  appear 
  merely 
  as 
  transverse 
  striae 
  

   becoming 
  obsolete 
  near 
  the 
  periphery 
  : 
  apex 
  acute 
  : 
  spire 
  with 
  

   the 
  outlines 
  moderately 
  curvilinear 
  : 
  whorls 
  nine, 
  moderately 
  

   convex, 
  with 
  a 
  lightly 
  impressed 
  suture 
  : 
  aperture 
  large, 
  oblique, 
  

   moderately 
  effuse 
  below, 
  more 
  deeply 
  effuse 
  above: 
  labrum 
  

   much 
  advanced 
  along 
  the 
  middle, 
  thickened 
  by 
  a 
  broad 
  stout 
  

   varix 
  : 
  umbilicus 
  wanting. 
  

  

  Mean 
  divergence 
  about 
  30° 
  ; 
  length 
  .19 
  inch 
  ; 
  breadth 
  .07 
  

   inch 
  ; 
  length 
  of 
  spire 
  .115 
  inch. 
  

  

  Station. 
  — 
  Unknown. 
  

  

  ^a&ito^.— 
  Panama 
  ; 
  C. 
  B. 
  A. 
  ! 
  

  

  2 
  specimens 
  were 
  found 
  in 
  the 
  sand. 
  

  

  Var. 
  a 
  is 
  larger, 
  being 
  .24 
  inch 
  long. 
  

  

  