﻿426 
  Scientific 
  Intelligence. 
  

  

  total 
  thickness 
  is 
  more 
  than 
  600 
  meters. 
  The 
  various 
  biotas 
  are 
  

   not 
  yet 
  described, 
  and 
  for 
  the 
  present 
  the 
  correlation 
  with 
  the 
  

   Cenomanian 
  is 
  provisional. 
  c. 
  s. 
  

  

  4. 
  Die 
  Ayitike 
  Tierwelt 
  ; 
  by 
  Otto 
  Keller. 
  Zweiter 
  Band: 
  

   Vogel, 
  Reptilien, 
  Fische, 
  Insecten, 
  etc. 
  Pp. 
  xv, 
  618 
  ; 
  2 
  plates, 
  

   161 
  text 
  figures. 
  — 
  This 
  volume 
  completes 
  an 
  extremely 
  valuable 
  

   work 
  by 
  Otto 
  Keller, 
  of 
  which 
  the 
  first 
  part, 
  that 
  upon 
  the 
  mam- 
  

   mals, 
  was 
  reviewed 
  in 
  this 
  Journal 
  for 
  July, 
  1910. 
  The 
  present 
  

   is 
  necessarily 
  the 
  more 
  voluminous 
  part, 
  embracing 
  as 
  it 
  does 
  the 
  

   entire 
  animal 
  kingdom 
  below 
  the 
  mammals, 
  excepting, 
  of 
  course, 
  

   the 
  Protozoa, 
  which 
  from 
  the 
  nature 
  of 
  things 
  would 
  be 
  outside 
  

   the 
  pale 
  of 
  the 
  observation 
  of 
  the 
  ancients. 
  The 
  sources 
  of 
  the 
  

   material 
  are 
  from 
  the 
  literature 
  and 
  from 
  the 
  pictorial 
  arts 
  ; 
  

   sculpture, 
  painting, 
  mosaics 
  — 
  especially 
  those 
  from 
  Pompeii, 
  and 
  

   from 
  ancient 
  coins 
  and 
  medals. 
  

  

  The 
  book 
  is 
  of 
  great 
  value 
  and 
  importance, 
  though 
  a 
  few 
  errors, 
  

   mainly 
  of 
  classification, 
  have 
  crept 
  in, 
  such 
  as 
  the 
  placing 
  of 
  the 
  

   annelid 
  Aphrodite 
  aculeata 
  with 
  the 
  myriapods, 
  and 
  the 
  crusta- 
  

   cean 
  Oniscus 
  and 
  its 
  allies 
  under 
  the 
  annelids. 
  Under 
  the 
  reptiles 
  

   the 
  "Krocodiles" 
  are 
  made 
  to 
  include 
  not 
  only 
  the 
  true 
  Croco- 
  

   dilia 
  but 
  the 
  huge 
  monitor 
  lizards 
  also. 
  Pearls 
  and 
  pearl 
  fisheries 
  

   are 
  discussed 
  at 
  length. 
  Printing 
  and 
  illustrations 
  are 
  admirable, 
  

   greatly 
  enhancing 
  the 
  value 
  of 
  this 
  important 
  work. 
  r. 
  s. 
  l. 
  

  

  5. 
  A 
  Manual 
  of 
  Petrology 
  ; 
  by 
  F. 
  P. 
  Mexnell. 
  8° 
  ; 
  pp. 
  

   256, 
  figs. 
  ]24. 
  London, 
  1913 
  (Chapman 
  & 
  Hall). 
  — 
  This 
  elemen- 
  

   tary 
  manual 
  is 
  founded 
  on 
  a 
  former 
  introductory 
  w 
  T 
  ork 
  by 
  the 
  

   author 
  published 
  some 
  years 
  ago. 
  So 
  little 
  remains 
  of 
  the 
  former 
  

   publication, 
  however, 
  that 
  it 
  may 
  be 
  considered 
  a 
  new 
  and 
  inde- 
  

   pendent 
  work. 
  It 
  is 
  designed 
  to 
  give 
  a 
  general 
  introduction 
  to 
  

   the 
  whole 
  field 
  covered 
  by 
  the 
  term 
  " 
  petrology 
  " 
  and 
  conse- 
  

   quently 
  suffers 
  those 
  disadvantages 
  which 
  the 
  compression 
  of 
  so 
  

   much 
  material 
  into 
  such 
  a 
  narrow 
  compass 
  necessarily 
  entails. 
  

   For 
  the 
  treatment 
  of 
  the 
  rock-forming 
  minerals, 
  their 
  optical 
  

   and 
  other 
  properties 
  ; 
  the 
  origin, 
  classification 
  and 
  description, 
  

   including 
  their 
  micropetrography, 
  of 
  the 
  igneous 
  rocks, 
  sedimen- 
  

   tary 
  rocks, 
  metamorphism 
  in 
  its 
  varied 
  aspects, 
  alteration 
  of 
  

   rocks, 
  their 
  chemistry 
  ; 
  radio-active 
  properties, 
  etc., 
  etc., 
  are 
  all 
  

   among 
  the 
  subjects 
  included. 
  The 
  author, 
  who 
  is 
  curator 
  of 
  the 
  

   Rhodesia 
  Museum, 
  and 
  whose 
  field 
  experience 
  has 
  been 
  largely 
  

   gained 
  in 
  South 
  Africa, 
  has 
  drawn 
  his 
  illustrative 
  material 
  to 
  a 
  

   great 
  extent 
  from 
  that 
  region, 
  and 
  this 
  gives 
  the 
  work 
  a 
  corre- 
  

   spondingly 
  local 
  character. 
  

  

  For 
  classification 
  of 
  the 
  igneous 
  rocks 
  the 
  writer 
  divides 
  them 
  

   first, 
  geologically 
  into 
  plutonics 
  (large 
  masses), 
  intrusives 
  (dikes), 
  

   and 
  effusives, 
  and 
  these 
  are 
  subdivided, 
  according 
  to 
  the 
  silica 
  

   content, 
  into 
  acid 
  (65 
  per 
  cent 
  + 
  ), 
  sub-acid 
  (60-65 
  per 
  cent), 
  sub- 
  

   basic 
  (55-60 
  per 
  cent), 
  basic 
  (45-55 
  per 
  cent) 
  and 
  ultra 
  basic 
  

   ( 
  — 
  45 
  per 
  cent). 
  Further 
  subdivision 
  than 
  this 
  he 
  thinks 
  is, 
  at 
  

   present, 
  to 
  be 
  deprecated. 
  

  

  