﻿1078 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  Subgenus 
  Antiptychina, 
  Zittel. 
  1883. 
  

  

  Shells 
  elongate, 
  brachial 
  valve 
  with 
  broad 
  median 
  sinus, 
  having 
  

   elevated 
  margins 
  and 
  a 
  stout 
  plication 
  at 
  its 
  base. 
  Dental 
  plates 
  

   and 
  median 
  dorsal 
  septum 
  well 
  developed. 
  Loop 
  long 
  and 
  fim- 
  

   briate. 
  

  

  Figs. 
  573-675. 
  Antiptychina 
  inversa, 
  Quenstedt 
  (sp.). 
  (Quknstedt.) 
  

  

  (Type, 
  Antiptychina 
  bivallata, 
  Deslongchamps 
  (sp.). 
  Jurassic 
  — 
  

   Cretaceous.) 
  

  

  Subgenus 
  Microthyris, 
  Deslongchamps. 
  1884. 
  

  

  Synonym; 
  Ornithella, 
  Deslongchamps, 
  1884. 
  

   Elongate-oval 
  shells 
  with 
  smooth 
  surface, 
  abrupt 
  anterior 
  

   slopes, 
  dental 
  plates 
  and 
  long 
  loop. 
  

  

  Figs. 
  576-578. 
  Microthyris 
  lagenalis, 
  Schlothelm 
  (sp.). 
  (Davidson.) 
  

  

  (Type, 
  Microthyris 
  lagenalis, 
  Schlotheim 
  (sp.). 
  Jurassic.) 
  

  

  136 
  

  

  