﻿1090 
  Forty- 
  seventh 
  Report 
  on 
  the 
  State 
  Museum, 
  

  

  Type, 
  Platidia 
  anomioides, 
  Scacchi 
  (sp.). 
  

  

  Distribution. 
  Recent 
  (Lusitanian, 
  Calif 
  ornian, 
  Magellanian, 
  

   Caribbean 
  and 
  Transatlantic 
  Provinces). 
  

  

  Megathyris, 
  d'Orbigny. 
  1847. 
  

  

  Synonym 
  ; 
  Argiope, 
  Deslongchamps, 
  1842. 
  

  

  Shells 
  transversely 
  elongate; 
  hinge-line 
  long 
  and 
  straight, 
  

  

  equaling 
  the 
  greatest 
  diameter 
  of 
  the 
  valves. 
  Cardinal 
  area 
  well 
  

  

  developed 
  on 
  both 
  valves 
  Foramen 
  

  

  large, 
  oval, 
  deltidial 
  plates 
  small. 
  In 
  

  

  the 
  pedicle-valve 
  there 
  is 
  a 
  median 
  

  

  septnm 
  and 
  two 
  low 
  lateral 
  septa. 
  

  

  Brachial 
  valve 
  with 
  prominent 
  Car- 
  

   lies. 
  634, 
  685. 
  Megathyris 
  decollate* 
  ^^ 
  procegs 
  and 
  three 
  Qr 
  five 
  gepta 
  

   Chemnitz 
  (sp.). 
  n, 
  foramen; 
  o, 
  deltidial 
  t 
  . 
  . 
  

  

  plates; 
  g, 
  crura; 
  i, 
  lobed 
  extension 
  of 
  lying 
  in 
  front 
  of 
  the 
  visceral 
  region. 
  

  

  brachial 
  supports. 
  (Bronn.) 
  Qf 
  ^^ 
  Qne 
  septum 
  ig 
  me 
  dian! 
  

  

  Brachidium 
  consisting 
  of 
  a 
  simple 
  continuous 
  lamellae 
  with 
  broad 
  

   oral 
  processes 
  and 
  divided 
  into 
  four 
  lobes 
  by 
  the 
  median 
  and 
  first 
  

   pair 
  of 
  lateral 
  septa. 
  The 
  brachial 
  disk 
  is 
  likewise 
  divided 
  into 
  

   four 
  lobes. 
  

  

  Type, 
  Megathyris 
  decollata, 
  Chemnitz 
  (sp.). 
  

  

  Distribution. 
  Jurassic 
  — 
  Recent 
  (Lusitanian 
  Province). 
  

  

  Cistella, 
  Gray. 
  1850. 
  

   Exteriorly 
  like 
  Megathyris. 
  Interior 
  of 
  the 
  valves 
  with 
  

   median 
  but 
  no 
  lateral 
  septa. 
  Brachial 
  lamella 
  bilobed 
  by 
  the 
  

   median 
  septum 
  to 
  which 
  it 
  is 
  partially 
  attached. 
  

  

  Figs. 
  636-638. 
  Cistella 
  cuneata, 
  Risso 
  (sp.). 
  Davidson. 
  

  

  Type, 
  Cistella 
  cuneata, 
  Pis 
  so 
  (sp.). 
  

  

  Distribution. 
  Cretaceous 
  — 
  Recent 
  (Boreal, 
  Lusitanian 
  and 
  

   Caribbean 
  Provinces). 
  

  

  148 
  

  

  

  