﻿MACROSEMIIDJE. 
  163 
  

  

  Family 
  MACROSEMIID^E. 
  

  

  Trunk 
  elongate 
  or 
  elongate-fusiform, 
  more 
  or 
  less 
  laterally 
  com- 
  

   pressed. 
  Cranial 
  and 
  facial 
  bones 
  moderately 
  robust 
  or 
  delicate, 
  

   and 
  opercular 
  apparatus 
  complete; 
  mandibular 
  suspensorium 
  ver- 
  

   tical 
  or 
  inclined 
  forwards, 
  and 
  gape 
  of 
  mouth 
  small 
  ; 
  marginal 
  teeth 
  

   styliform, 
  inner 
  teeth 
  similar 
  or 
  tubercular. 
  Notochord 
  persistent, 
  

   the 
  vertebra 
  never 
  advancing 
  beyond 
  the 
  annular 
  stage. 
  Fin-rays 
  

   robust, 
  the 
  majority 
  well-spaced, 
  articulated 
  and 
  divided 
  distally 
  ; 
  

   fulcra 
  variable 
  ; 
  dorsal 
  fin 
  elongated, 
  usually 
  extending 
  at 
  least 
  half 
  

   the 
  length 
  of 
  the 
  trunk. 
  Scales 
  rhombic. 
  

  

  The 
  cranial 
  osteology 
  of 
  the 
  If 
  acrosemiidae 
  is 
  as 
  yet 
  very 
  un- 
  

   satisfactorily 
  known, 
  the 
  only 
  illustration 
  of 
  importance 
  hitherto 
  

   published 
  being 
  that 
  of 
  the 
  skull 
  of 
  Macrosemius 
  by 
  K. 
  A. 
  von 
  

   Zittel, 
  reproduced 
  below 
  (fig. 
  29). 
  The 
  basicranial 
  axis 
  is 
  always 
  

   straight 
  and 
  nearly 
  parallel 
  with 
  the 
  hinder 
  portion 
  of 
  the 
  cranial 
  

   roof 
  ; 
  there 
  is 
  no 
  interorbital 
  septum 
  ; 
  the 
  cleft 
  of 
  the 
  mouth 
  is 
  

   horizontal, 
  and 
  the 
  rostrum 
  does 
  not 
  project 
  beyond 
  the 
  mandible, 
  

  

  Fig. 
  29. 
  

  

  Macrosemius 
  latiusculus 
  ; 
  head 
  and 
  opercular 
  apparatus, 
  left 
  

   lateral 
  aspect 
  (after 
  Zittel). 
  

   ar., 
  angular 
  ; 
  br., 
  branehiostegal 
  rays 
  ; 
  cl., 
  clavicle 
  ; 
  d., 
  dentary 
  ; 
  hy., 
  cerato 
  

   hyal 
  ; 
  mx., 
  maxilla 
  ; 
  o., 
  orbit 
  ; 
  op., 
  operculum 
  ; 
  p.op., 
  preoperculum 
  ; 
  

   pa., 
  parietal 
  region 
  ; 
  pi., 
  pterygopalatine 
  arcade 
  ; 
  pmx., 
  premaxilla 
  : 
  

   psph., 
  parasphenoid 
  ; 
  qu., 
  quadrate 
  ; 
  s.op., 
  suboperculum 
  ; 
  spl., 
  splenial 
  : 
  

   vo., 
  vomer. 
  

  

  In 
  Macrosemius 
  the 
  sclerotic 
  of 
  the 
  eye 
  is 
  ossified, 
  and 
  the 
  cheek- 
  

   plates 
  seem 
  to 
  have 
  been 
  very 
  delicate. 
  The 
  mandibular 
  suspen- 
  

   sorium 
  is 
  inclined 
  so 
  much 
  forwards 
  that 
  the 
  articulation 
  of 
  the 
  

   quadrate 
  (qu.) 
  is 
  beneath 
  the 
  front 
  margin 
  of 
  the 
  orbit 
  (o.). 
  The 
  

  

  m2 
  

  

  