﻿1082 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  branches 
  near 
  the 
  transverse 
  band 
  with 
  the 
  descending 
  branches 
  

   just 
  in 
  front 
  of 
  the 
  oral 
  processes. 
  

  

  Figs. 
  595, 
  596. 
  Laqueus 
  Californicus, 
  Koch 
  (sp."). 
  (Davidson.) 
  

  

  Type, 
  Laqueus 
  Californicus 
  Koch 
  (sp.). 
  

  

  Distribution. 
  Recent 
  (Boreal, 
  Japanese 
  and 
  Californian 
  Prov- 
  

   inces). 
  

  

  Trigonosemus, 
  Koenig. 
  1825. 
  

  

  Synonyms; 
  Fissurirostra, 
  d'Orbigny, 
  1847; 
  Fissirostra, 
  

   d'Orbigny, 
  1848 
  ; 
  Delthyridea, 
  King, 
  1850. 
  

  

  Shells 
  planoconvex 
  ; 
  surface 
  radially 
  plicate. 
  Pedicle-valve 
  

   with 
  arched 
  and 
  prominent 
  beak, 
  sharply 
  defined 
  cardinal 
  area, 
  

  

  Figs. 
  597-600. 
  Trigonosemus 
  elegans, 
  Koenig. 
  (Davidson.) 
  

  

  and 
  minute 
  apical 
  foramen 
  bounded 
  beneath 
  by 
  coalesced 
  deltidial 
  

   plates. 
  Cardinal 
  process 
  highly 
  developed, 
  bilobed. 
  Loop 
  as 
  in 
  

   Terebratella, 
  but 
  more 
  narrow 
  and 
  elongate. 
  

  

  Type, 
  Trigonosemus 
  elegans, 
  Koenig. 
  

  

  Distribution. 
  Cretaceous. 
  

  

  140 
  

  

  