﻿1004 
  Forty-seventh 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  slightly 
  more 
  than 
  one 
  entire 
  volution. 
  Toward 
  the 
  anterior 
  

   margins 
  of 
  the 
  primary 
  lamella? 
  a 
  strong 
  jugum 
  is 
  given 
  off, 
  its 
  

   lateral 
  branches 
  projected 
  very 
  obliquely 
  backward, 
  sometimes 
  

   scarcely 
  rising 
  between 
  the 
  coils, 
  the 
  union 
  f 
  orming^a 
  broad 
  angle 
  

  

  Fig. 
  387. 
  

   The 
  brachidium 
  of 
  Protozyga 
  exigua, 
  Hall. 
  

  

  on 
  the 
  anterior 
  margin 
  with 
  a 
  subacute 
  process 
  on 
  the 
  outer 
  

   margin. 
  

  

  (Type, 
  Protozyga 
  exigua, 
  Hall. 
  Lower 
  Silurian 
  (Trenton 
  

   limestone).) 
  

  

  Hallina, 
  K 
  H. 
  Winchell 
  and 
  Schuchert. 
  1892. 
  

   (Plate 
  40, 
  figs. 
  6-8.) 
  

  

  Shells 
  small, 
  oval 
  in 
  outline 
  ; 
  valves 
  biconvex 
  and 
  covered 
  with 
  

   numerous 
  fine, 
  sharp 
  radial 
  plications. 
  Brachidium 
  consisting 
  of 
  

   lateral 
  processes 
  making 
  somewhat 
  less 
  than 
  a 
  single 
  volution 
  

  

  Fig. 
  388. 
  

  

  Fig. 
  389. 
  

  

  Fig. 
  390. 
  

  

  Preparations 
  showing 
  the 
  structure 
  of 
  the 
  brachidium 
  in 
  Hallina 
  Saffordi, 
  Winchell 
  ; 
  and 
  

   Schuchert. 
  

  

  Fig. 
  388. 
  The 
  pedicle-valve 
  cut 
  so 
  as 
  to 
  show 
  the 
  tips 
  of 
  the 
  ascending 
  lamellas. 
  

   Fig. 
  389. 
  The 
  opposite 
  side, 
  showing 
  the 
  form 
  of 
  the 
  primary 
  lamellae 
  as 
  far 
  as 
  the 
  base 
  of 
  

  

  the 
  jugum, 
  and 
  the 
  character 
  of 
  the 
  latter. 
  

   Fig. 
  390. 
  View 
  showing 
  the 
  brachidium 
  in 
  profile. 
  

  

  and 
  united 
  by 
  a 
  simple, 
  posteriorly 
  directed! 
  7 
  jugum, 
  situated 
  near 
  

   their 
  anterior 
  upward 
  curvature. 
  

  

  Type, 
  Hallina 
  tiaffordi, 
  N. 
  H. 
  Winchell 
  and 
  Schuchert. 
  

  

  Distribution. 
  Lower 
  Silurian 
  (Trenton 
  limestone.) 
  

  

  62 
  

  

  