﻿484 
  ACTIN0PTERYG1I. 
  

  

  P. 
  1101. 
  Imperfect 
  specimen 
  labelled 
  by 
  Egerton 
  ; 
  Swanage. 
  There 
  

   are 
  crushed 
  remains 
  of 
  ring-vertebra?, 
  and 
  the 
  origin 
  of 
  

   the 
  dorsal 
  fin 
  appears 
  to 
  be 
  directly 
  opposed 
  to 
  that 
  of 
  

   the 
  anal. 
  Egerton 
  Coll. 
  

  

  Pleuropholis 
  crassicaudata, 
  Egerton. 
  

  

  [Plate 
  XIV. 
  fig. 
  5.] 
  

  

  1858. 
  Pleuropholis 
  crassicaudus, 
  Sir 
  P. 
  Egerton, 
  Figs. 
  & 
  Descript. 
  Brit. 
  

   Organic 
  Remains, 
  dec. 
  ix. 
  (Mem. 
  Geol. 
  Surv.), 
  no. 
  7, 
  p. 
  3, 
  pi. 
  vii. 
  

   fig. 
  2. 
  

  

  Type. 
  Imperfect 
  fish 
  ; 
  collection 
  of 
  Rev. 
  P. 
  B. 
  Brodie. 
  

  

  A 
  small, 
  comparatively 
  robust 
  species 
  attaining 
  a 
  length 
  of 
  about 
  

   0'06. 
  Length 
  of 
  head 
  with 
  opercular 
  apparatus 
  about 
  equalling 
  

   the 
  maximum 
  depth 
  of 
  the 
  trunk, 
  and 
  contained 
  slightly 
  more 
  

   than 
  five 
  times 
  in 
  the 
  total 
  length 
  of 
  the 
  fish 
  ; 
  width 
  of 
  caudal 
  

   pedicle 
  equalling 
  about 
  two-thirds 
  the 
  depth 
  of 
  the 
  flank-scales 
  

   in 
  the 
  middle 
  of 
  the 
  abdominal 
  region. 
  Pelvic 
  fins 
  arising 
  mid- 
  

   way 
  between 
  the 
  pectorals 
  and 
  the 
  anal 
  ; 
  distance 
  between 
  the 
  

   origin 
  of 
  the 
  pectoral 
  and 
  anal 
  fins 
  nearly 
  twice 
  as 
  great 
  as 
  that 
  

   between 
  the 
  origin 
  of 
  the 
  latter 
  and 
  the 
  caudal. 
  Scales 
  smooth, 
  not 
  

   serrated. 
  

  

  This 
  definition 
  of 
  the 
  species 
  is 
  based 
  upon 
  the 
  specimen 
  recorded 
  

   below. 
  

  

  Form. 
  6f 
  Loc. 
  Lower 
  Purbeckian 
  (" 
  Insect 
  Bed 
  ") 
  : 
  Durdlestone 
  

   Bay, 
  Swanage, 
  Dorsetshire. 
  

  

  43615. 
  Well-preserved 
  fish 
  shown 
  of 
  the 
  natural 
  size 
  in 
  PL 
  XIY. 
  

   fig. 
  5 
  ; 
  in 
  marl 
  from 
  the 
  " 
  Dirt 
  Bed 
  " 
  series. 
  The 
  propor- 
  

   tions 
  of 
  the 
  head 
  and 
  relatively 
  large 
  eye 
  are 
  indicated, 
  

   and 
  the 
  squamation 
  is 
  distinct. 
  Of 
  the 
  fins 
  only 
  the 
  

   dorsal 
  is 
  entirely 
  wanting, 
  and 
  the 
  others 
  exhibit 
  traces 
  

   of 
  fulcra. 
  The 
  scales 
  are 
  shown 
  to 
  be 
  united 
  by 
  peg- 
  

   and-socket 
  articulation, 
  and 
  there 
  are 
  four 
  series 
  beneath 
  

   the 
  deepened 
  flank- 
  scales, 
  while 
  only 
  two 
  or 
  three 
  

   can 
  be 
  recognized 
  above. 
  The 
  lateral 
  line 
  passes 
  

   from 
  the 
  hinder 
  angle 
  of 
  the 
  cranium 
  across 
  the 
  first 
  

   (and 
  perhaps 
  the 
  second) 
  deepened 
  flank-scale, 
  is 
  then 
  

   deflected 
  down 
  the 
  second 
  (perhaps 
  third) 
  scale, 
  and 
  

   thence 
  passes 
  directly 
  along 
  the 
  upper 
  series 
  of 
  ventral 
  

   scales, 
  which 
  are 
  slightly 
  deeper 
  than 
  those 
  below. 
  

  

  Purchased, 
  1872. 
  

  

  