﻿NIAGARA 
  FALLS 
  AND 
  VICINITY 
  269 
  

  

  intrathecal 
  — 
  within 
  the 
  theca; 
  endothecal 
  

  

  introverted 
  — 
  turned 
  apex 
  to 
  apex; 
  applied 
  to 
  the 
  spirals 
  of 
  brachiopods 
  

  

  involute 
  — 
  rolled 
  up, 
  as 
  a 
  Nautilus 
  shell 
  

  

  joints 
  — 
  component 
  segments 
  of 
  the 
  stem 
  of 
  a 
  crinoid 
  

  

  jugum 
  — 
  yoke-like 
  connection 
  between 
  the 
  two 
  parts 
  of 
  the 
  brachidium 
  of 
  

   a 
  brachiopod 
  

  

  keel 
  — 
  strong 
  central 
  carina 
  or 
  ridge 
  (Taeniopora) 
  

  

  lacrjrmiform 
  — 
  tear-form; 
  drop 
  shaped 
  — 
  pear 
  shaped, 
  but 
  without 
  the 
  lateral 
  

   contractions 
  

  

  lamellar 
  — 
  disposed 
  in 
  lamellae 
  or 
  layers 
  

  

  lamellibranch 
  — 
  leaf-gilled, 
  the 
  class 
  of 
  molluska 
  with 
  bivalved 
  shell, 
  to 
  which 
  

   the 
  oyster 
  and 
  clam 
  belong; 
  pelecypod 
  

  

  lamelliform 
  — 
  having 
  the 
  '^orm 
  of 
  a 
  leaf 
  or 
  lamella 
  

  

  lamellose 
  — 
  made 
  up 
  of 
  lamellae 
  

  

  lamina 
  — 
  a 
  thin 
  plate 
  or 
  scale 
  

  

  lateral 
  gemmation 
  — 
  a 
  budding 
  from 
  the 
  sides, 
  as 
  in 
  some 
  corals 
  

  

  lateral 
  teeth 
  — 
  ridge-like 
  projections 
  on 
  either 
  side 
  of 
  the 
  beak, 
  in 
  the 
  in- 
  

   terior 
  of 
  lamellibranch 
  shells 
  

  

  laviformia 
  — 
  primitive 
  order 
  of 
  crinoids 
  

  

  ligament 
  — 
  external 
  structure 
  for 
  opening 
  the 
  valves 
  in 
  the 
  pelecypoda 
  

  

  limb 
  — 
  lateral 
  area 
  or 
  marginal 
  band 
  of 
  the 
  cephalon 
  of 
  trilobites 
  on 
  either 
  

   side 
  of 
  the 
  glabella, 
  corresponding 
  to 
  a 
  pleuron 
  of 
  the 
  thoracic 
  region 
  

  

  lines 
  of 
  growth 
  — 
  lines 
  marking 
  the 
  periodic 
  increase 
  in 
  size, 
  in 
  shells 
  

  

  linguiform 
  — 
  tongue-shaped 
  

  

  linguloid 
  — 
  tongue-shaped; 
  like 
  Lingula 
  

  

  lip 
  — 
  margins 
  of 
  the 
  aperture 
  of 
  univalve 
  shell 
  

  

  listrium 
  — 
  depressed 
  area 
  surrounding 
  the 
  pedicle 
  opening 
  in 
  the 
  pedi:le 
  

   valve 
  of 
  Orbiculoidea 
  and 
  other 
  discinoid 
  brachiopods 
  

  

  lithic 
  — 
  pertaining 
  to 
  stone 
  

  

  living 
  chamber 
  — 
  the 
  last 
  chamber 
  in 
  the 
  shell 
  of 
  a 
  cephalopod, 
  which 
  is 
  

   occupied 
  by 
  the 
  animal 
  

  

  lobes 
  — 
  backward 
  bending 
  portions 
  of 
  the 
  suture 
  of 
  cephalopod 
  shells 
  

  

  lophophore 
  — 
  ciliated 
  or 
  tentaculated, 
  oral 
  disk 
  of 
  bryozoa; 
  the 
  oral 
  disk 
  

   and 
  brachia 
  of 
  brachiopods 
  

  

  lunarium 
  — 
  more 
  or 
  less 
  thickened 
  portion 
  of 
  the 
  posterior 
  wall 
  of 
  the 
  cell 
  

   in 
  many 
  paleozoic 
  bryozoa, 
  which 
  is 
  lunate 
  or 
  curved 
  to 
  a 
  shorter 
  

   radius, 
  and 
  usually 
  projects 
  above 
  the 
  plane 
  of 
  the 
  cell 
  aperture 
  

  

  lunule 
  — 
  depression 
  in 
  front 
  of 
  the 
  beak 
  of 
  pelecypod 
  shells 
  

  

  macerate 
  — 
  softening 
  and 
  disintegrating 
  by 
  immersion 
  in 
  water 
  

  

  macrocorallites 
  — 
  the 
  larger 
  corallites 
  in 
  a 
  compound 
  corallum 
  

  

  maculae 
  — 
  irregular, 
  usually 
  depressed, 
  areas 
  on 
  the 
  celluliferous 
  face 
  of 
  a 
  

  

  bryozoan 
  frond, 
  which 
  are 
  free 
  from 
  cells, 
  or 
  otherwise 
  differentiated 
  

   mandibles 
  — 
  first 
  upper 
  or 
  outer 
  pair 
  of 
  jaws 
  of 
  Crustacea 
  and 
  insects 
  

  

  