﻿VON 
  SEEBACH 
  JTJKASSIC 
  EOCKS. 
  33 
  

  

  Von 
  Seebach's 
  accompanying 
  map 
  shows 
  the 
  several 
  outcropping 
  

   patches 
  of 
  Lower, 
  Middle, 
  and 
  Upper 
  " 
  Jura 
  " 
  between 
  Hanover 
  

   and 
  Gotha, 
  and 
  from 
  the 
  Rhine 
  to 
  the 
  Elbe. 
  The 
  several 
  divisions 
  

   of 
  this 
  formation 
  in 
  North-west 
  Germany 
  form 
  the 
  subject 
  of 
  the 
  

   second 
  part 
  of 
  the 
  geognostical 
  half 
  of 
  the 
  book 
  (pp. 
  13-60), 
  beginning 
  

   with 
  a 
  few 
  lines 
  on 
  the 
  Avicula-contorta-beds, 
  which, 
  whether 
  really 
  

   Triassic 
  or 
  Jurassic, 
  naturally 
  are 
  not 
  separable 
  from 
  the 
  base 
  of 
  the 
  

   Lias 
  in 
  a 
  full 
  description 
  of 
  strata. 
  Von 
  Seebach 
  takes 
  as 
  the 
  lowest 
  

   really 
  Jurassic 
  bed 
  in 
  Hanover 
  an 
  iron 
  black 
  shale, 
  which 
  lies 
  on 
  the 
  

   uppermost 
  bituminous 
  sandstone 
  (with 
  Cardium 
  Hhceticiwn) 
  of 
  the 
  

   Avicula-contorta-zone, 
  and 
  is 
  10-12 
  feet 
  thick, 
  without 
  fossils, 
  but 
  

   quite 
  similar 
  to 
  the 
  true 
  Lias 
  above. 
  

  

  A. 
  The 
  Lias. 
  — 
  The 
  Lower 
  Lias 
  in 
  North-western 
  Germany 
  has 
  

   four 
  members, 
  the 
  Middle 
  three, 
  and 
  the 
  Upper 
  two, 
  according 
  to 
  the 
  

   divisions 
  established 
  for 
  France 
  and 
  South 
  Germany. 
  The 
  Lower 
  

   Lias 
  in 
  North 
  Germany 
  is 
  difficult 
  to 
  work 
  out, 
  though 
  most 
  minutely 
  

   subdivided 
  in 
  Swabia. 
  1. 
  The 
  Psilonotus-beds, 
  with 
  Ammonites 
  

   Johnstoni. 
  2. 
  The 
  Angulatus-beds, 
  with 
  A. 
  angulatus 
  and 
  Unicar- 
  

   dium 
  cardioides. 
  3. 
  The 
  Arietes-beds, 
  with 
  A. 
  Bucklandi, 
  Lima 
  

   gigantea, 
  A. 
  Conybeari, 
  and 
  Gryphoza 
  arenata. 
  4. 
  The 
  Planicosta- 
  

   beds, 
  with 
  A. 
  planicosta 
  and 
  A. 
  ziphius. 
  5. 
  The 
  Brevispina-beds, 
  

   with 
  A. 
  brevispina, 
  A. 
  binotatus, 
  A. 
  Jamesoni, 
  Rhynclionella 
  

   furcillata, 
  Terebratula 
  numismatis, 
  and 
  Spirifer 
  rostratus. 
  6. 
  The 
  

   Capricornus-beds, 
  with 
  A. 
  capricornus, 
  A. 
  curvicornus, 
  and 
  Avicula 
  

   cygnipes. 
  7. 
  The 
  Amaltheus-beds, 
  with 
  A. 
  margaritatus, 
  A. 
  spinatus, 
  

   Belemnites 
  compressus, 
  Gresslya 
  ventricosa, 
  Inoceramus 
  substriaius, 
  

   and 
  Pecten 
  cequivalvis. 
  8. 
  The 
  Posidonise-beds, 
  with 
  Belemnites 
  

   irregidaris, 
  A. 
  Lythensis, 
  A. 
  borealis, 
  A. 
  communis, 
  Inoceramus 
  amyg- 
  

   daloides, 
  Avicula 
  substriata, 
  and 
  Discina 
  papyracea. 
  9. 
  The 
  Juren- 
  

   sis-beds, 
  with 
  Belemnites 
  irregularis, 
  A. 
  dispensus, 
  A. 
  striatulus, 
  A. 
  

   Germanii, 
  A. 
  insignis, 
  and 
  A. 
  Jurensis. 
  

  

  B. 
  The 
  Dogger, 
  between 
  the 
  Jurensis-beds 
  and 
  the 
  Macrocephalus- 
  

   beds, 
  is 
  in 
  North-western 
  Germany 
  divisible 
  into 
  six, 
  perhaps 
  

   seven 
  members, 
  rather 
  difficult 
  of 
  recognition 
  lithologically, 
  but 
  well 
  

   marked 
  by 
  fossils. 
  1. 
  Opalinus-beds, 
  with 
  the 
  following, 
  placed 
  

   according 
  to 
  their 
  value 
  : 
  — 
  Nucula 
  Hammeri, 
  A. 
  radiosus, 
  Trigonia 
  

   navis, 
  Cerithium 
  armatum, 
  A. 
  affinis, 
  Astarte 
  complanata, 
  Belemnites 
  

   Bhenanus, 
  and 
  A. 
  opalinus. 
  2. 
  The 
  Inoceramus-polyplocus-beds, 
  

   with 
  /. 
  polyplocus, 
  Gresslya 
  donaciformis, 
  Pholadomya 
  transversa, 
  

   P. 
  decorata, 
  Goldf. 
  (Zieten?), 
  A. 
  Murchisonm, 
  and 
  A. 
  near 
  A, 
  

   cycloides. 
  The 
  Coronatus-beds, 
  with 
  Belemnites 
  giganteus 
  in 
  both 
  

   its 
  subdivisions, 
  and 
  with 
  Gresslya 
  abducta, 
  A. 
  Breckenridgii, 
  A. 
  

   pinguis, 
  A. 
  Gervillii, 
  A. 
  Sauzei, 
  Modiola 
  cuneata, 
  and 
  Belemnites 
  

  

  Gingensis 
  in 
  the 
  lower, 
  and 
  Perna 
  isognomonoides 
  and 
  A, 
  Hum- 
  

   phriesianus 
  in 
  the 
  upper 
  division. 
  4. 
  The 
  Parkinsoni-beds. 
  5. 
  The 
  

   Ostrea-Knorii-beds, 
  with 
  Rhynchonella 
  varians, 
  Avicula 
  ec7iinata(2), 
  

   Ostrea 
  Knorii, 
  Astarte 
  pulla, 
  Avicula 
  f 
  err 
  uginea, 
  Belemnites 
  Beyricki, 
  

   Trigonia 
  interlaivigata, 
  and 
  A. 
  orbis. 
  7. 
  The 
  ferruginous 
  limestone 
  

   of 
  the 
  Cornbrash, 
  with 
  Avicula 
  echinata, 
  Echinobrissus 
  clunicularis, 
  

   A. 
  posterus, 
  and 
  Belemnites 
  hastatus. 
  

  

  