﻿Geology. 
  .231 
  

  

  edited 
  by 
  S. 
  Chapman. 
  The 
  material 
  is 
  appropriately 
  presented 
  

   in 
  five 
  chapters 
  the 
  captions 
  of 
  which 
  are: 
  I 
  Early 
  Life, 
  1791- 
  

   1813; 
  II 
  Scientific 
  Training, 
  1813-1831; 
  III 
  Electrical 
  

   Researches 
  (First 
  Period), 
  1831-1845; 
  IV 
  Electrical 
  Researches 
  

   (Second 
  Period), 
  1845-1855; 
  and 
  V 
  Old 
  Age, 
  1855-1867. 
  The 
  

   author's 
  style 
  is 
  smooth 
  and 
  attractive, 
  and 
  the 
  subject-matter 
  

   is 
  so 
  important 
  and 
  inspiring 
  that, 
  having 
  once 
  commenced 
  the 
  

   first 
  chapter, 
  the 
  reader 
  finds 
  it 
  very 
  difficult 
  to 
  lay 
  aside 
  the 
  

   little 
  book 
  before 
  the 
  last 
  page 
  has 
  been 
  reached. 
  It 
  is 
  to 
  be 
  

   hoped 
  that 
  this 
  volume 
  will 
  be 
  generally 
  brought 
  to 
  the 
  attention 
  

   of 
  graduate 
  students 
  in 
  physics 
  and 
  chemistry 
  so 
  that 
  they 
  may 
  

   be 
  lured 
  into 
  the 
  fascinating, 
  but 
  too 
  often 
  neglected, 
  field 
  of 
  

   the 
  history 
  of 
  the 
  great 
  pioneers 
  of 
  science. 
  The 
  only 
  drawback 
  

   to 
  the 
  book 
  is 
  the 
  very 
  poor 
  quality 
  of 
  the 
  paper 
  upon 
  which 
  the 
  

   pages 
  are 
  printed. 
  h. 
  s. 
  u. 
  

  

  II. 
  Geology. 
  

  

  1. 
  Appendages 
  of 
  Trilooites; 
  by 
  Chasles 
  D. 
  Walcott. 
  

   Smithson. 
  Misc. 
  Coll., 
  67, 
  No. 
  4, 
  pp. 
  115-216, 
  pis. 
  14-42, 
  text 
  

   figs. 
  1-3, 
  1918. 
  — 
  When 
  a 
  young 
  man, 
  the 
  present 
  Secretary 
  of 
  

   the 
  Smithsonian 
  Institution 
  became 
  interested 
  in 
  trilobites, 
  and 
  

   in 
  1876 
  published 
  his 
  first 
  description 
  of 
  the 
  ventral 
  anatomy 
  

   of 
  this 
  group. 
  These 
  first 
  studies 
  culminated 
  in 
  1881, 
  and 
  were 
  

   published 
  by 
  the 
  Museum 
  of 
  Comparative 
  Zoology, 
  the 
  specimens 
  

   having 
  in 
  the 
  meantime 
  been 
  transferred 
  to 
  Louis 
  Agassiz; 
  

   they 
  had 
  to 
  do 
  in 
  the 
  main 
  with 
  Calymene 
  and 
  Ceraurus, 
  and 
  

   remain 
  unique 
  to 
  this 
  day. 
  In 
  1894, 
  "Walcott 
  returned 
  to 
  the 
  

   subject, 
  developing 
  now 
  the 
  ventral 
  anatomy 
  of 
  Triarthrus. 
  

   During 
  the 
  past 
  eight 
  years 
  he 
  has 
  been 
  getting 
  from 
  the 
  Middle 
  

   Cambrian 
  of 
  British 
  Columbia 
  specimens 
  of 
  Neolenus 
  with 
  the 
  

   legs 
  preserved, 
  and 
  in 
  the 
  present 
  publication 
  he 
  brings 
  together 
  

   all 
  that 
  is 
  known 
  of 
  the 
  ventral 
  anatomy 
  of 
  the 
  trilobite 
  group, 
  

   with 
  an 
  abundance 
  of 
  photographs 
  and 
  drawings 
  interpreting 
  

   these 
  difficult 
  fossils. 
  The 
  work 
  contains 
  a 
  wealth 
  of 
  informa- 
  

   tion 
  regarding 
  Neolenus, 
  Triarthrus, 
  Calymene, 
  Ceraurus, 
  and 
  

   Isotelus, 
  and 
  will 
  long 
  remain 
  one 
  of 
  the 
  standards 
  on 
  trilobite 
  

   anatomy. 
  Restorations 
  of 
  the 
  three 
  first 
  named 
  genera 
  are 
  given. 
  

   The 
  author 
  states 
  that 
  this 
  is 
  his 
  last 
  word 
  on 
  the 
  subject, 
  since 
  he 
  

   does 
  not 
  again 
  expect 
  to 
  write 
  on 
  the 
  appendages. 
  of 
  the 
  trilobites. 
  

  

  Neolenus 
  is 
  a 
  specialized 
  trilobite, 
  with 
  a 
  large 
  pygidium, 
  and 
  

   one's 
  attention 
  is 
  at 
  once 
  attracted 
  to 
  its 
  long 
  and 
  powerful 
  

   posterior 
  crawling 
  legs. 
  In 
  this 
  respect 
  the 
  genus 
  is 
  very 
  unlike 
  

   the 
  primitive 
  Triarthrus. 
  Neolenus 
  also 
  has 
  two 
  long 
  and 
  

   spinose 
  caudal 
  rami, 
  organs 
  unknown 
  in 
  any 
  other 
  trilobite. 
  

   Its 
  exopodite 
  or 
  breathing 
  limb 
  is 
  again 
  unlike 
  that 
  of 
  any 
  other 
  

   form, 
  being 
  a 
  long, 
  un 
  jointed, 
  paddle-like 
  blade 
  replete 
  with 
  

   hollow, 
  hair 
  -like 
  tubes. 
  

  

  In 
  all 
  of 
  the 
  above 
  we 
  readily 
  accept 
  the 
  author's 
  views, 
  but 
  

  

  