﻿198 
  Mr. 
  C. 
  T. 
  Regan— 
  A 
  Synopsis 
  of 
  the 
  

  

  Exomegas 
  macrostomus, 
  Gill, 
  Proc. 
  U.S. 
  Nat. 
  Mus. 
  v. 
  1882, 
  p. 
  524 
  ; 
  

  

  Berg, 
  Coinniun. 
  Mus. 
  Buenos 
  Aires, 
  i. 
  1899, 
  p. 
  91. 
  

   Geotria 
  macrostoma, 
  Berg, 
  Ann. 
  Mus. 
  La 
  Plata, 
  Zool. 
  i. 
  1893, 
  p. 
  3, 
  

  

  pi. 
  i. 
  

   Geotria 
  macrostoma, 
  var. 
  gallegensis, 
  Smith, 
  Bih. 
  Svensk. 
  Vet.-Akad. 
  

  

  Handl. 
  xxvi. 
  iv. 
  no. 
  13, 
  p. 
  26, 
  pi. 
  iv. 
  

  

  Argentina 
  ; 
  Patagonia. 
  

  

  Recent 
  descriptions 
  show 
  that 
  this 
  species 
  is 
  a 
  true 
  Geotria 
  ; 
  

   the 
  supraoral 
  lamina 
  appears 
  to 
  have 
  the 
  same 
  form 
  as 
  in 
  the 
  

   other 
  species 
  of 
  the 
  genus 
  ; 
  the 
  infraoral 
  lamina 
  is 
  absent 
  or 
  

   deciduous, 
  but 
  this 
  may 
  be 
  the 
  case 
  in 
  G. 
  australis 
  also 
  ; 
  the 
  

   so-called 
  enlarged 
  outer 
  series 
  of 
  teeth 
  seem 
  to 
  be 
  the 
  fringes 
  

   of 
  the 
  disc. 
  

  

  3. 
  Petromyzon. 
  

  

  Petromyzon 
  (part.), 
  Linn. 
  Syst. 
  Nat. 
  ed. 
  10, 
  p. 
  230 
  (1758) 
  ; 
  Giinth. 
  

  

  Cat. 
  Fish. 
  viii. 
  p. 
  500 
  (1870). 
  

   Petromyzon, 
  Gray, 
  Choiidropt, 
  p. 
  143 
  (1851). 
  

   Bathymyzon, 
  Gill, 
  Proc. 
  U.S. 
  Nat. 
  Mus. 
  1883, 
  p. 
  254. 
  

  

  Disc 
  covered 
  with 
  radially 
  arranged 
  teeth. 
  A 
  single 
  

   narrow 
  bicuspid 
  supraoral 
  lamina 
  ; 
  infraoral 
  lamina 
  cuspi- 
  

   date. 
  Anterior 
  lingual 
  lamina 
  with 
  two 
  curved 
  denticulated 
  

   ridges 
  separated 
  by 
  a 
  median 
  longitudinal 
  groove. 
  Dorsal 
  

   fins 
  separate. 
  

  

  North 
  Atlantic 
  and 
  Mediterranean, 
  entering 
  rivers. 
  

  

  1. 
  Petromyzon' 
  marinus. 
  

  

  Petromyzon 
  marinus, 
  Linn. 
  Syst. 
  Nat. 
  ed. 
  10, 
  p. 
  230 
  (1758) 
  ; 
  Giinth. 
  

  

  Cat. 
  Fish. 
  viii. 
  p. 
  501 
  (1870) 
  ; 
  Day, 
  Fish. 
  Brit. 
  ii. 
  p. 
  356, 
  pi. 
  clxxviii. 
  

  

  (1884) 
  ; 
  Jord. 
  & 
  Everm. 
  Bull. 
  U.S. 
  Nat. 
  Mus. 
  xlvii. 
  1896, 
  p. 
  10; 
  

  

  Berg, 
  Bull. 
  Imp. 
  Acad. 
  St. 
  Petersb. 
  (5) 
  xxiv. 
  1906, 
  p. 
  176. 
  

   Bathymyzon 
  bairdii, 
  Gill, 
  Proc. 
  U.S. 
  Nat. 
  Mus. 
  1883, 
  p. 
  254 
  ; 
  Jord. 
  & 
  

  

  Everin. 
  t. 
  c. 
  p. 
  9. 
  

   Petromyzon 
  dorsatus, 
  Gage, 
  Wilder 
  Quarter 
  Century 
  Booh, 
  p. 
  425, 
  

  

  pis. 
  i., 
  iii., 
  & 
  vi. 
  fig. 
  19 
  (1893). 
  

   Petromyzon 
  marinus 
  unicolor, 
  Jord. 
  & 
  Everm. 
  t. 
  c. 
  p. 
  9. 
  

  

  Infraoral 
  lamina 
  with 
  7 
  to 
  9 
  cusps 
  ; 
  4 
  inner 
  labial 
  teeth 
  on 
  

   each 
  side 
  enlarged, 
  bicuspid. 
  

  

  North 
  Atlantic 
  and 
  Mediterranean, 
  entering 
  rivers 
  in 
  

   Europe 
  and 
  North 
  America. 
  

  

  1. 
  780 
  mm. 
  . 
  Dr. 
  F. 
  Day. 
  

  

  2. 
  600 
  mm. 
  Baltic. 
  Haslar 
  Coll. 
  

  

  3. 
  210 
  mm. 
  Scotland. 
  Dr. 
  Johnston. 
  

  

  4. 
  550 
  mm. 
  Lough 
  Neagh. 
  R. 
  Patterson, 
  Esq. 
  

  

  5. 
  630 
  mm. 
  Devonshire. 
  

  

  6. 
  800 
  mm. 
  . 
  London 
  Market. 
  

  

  7. 
  620 
  mm. 
  Holland. 
  Lidth 
  de 
  Jeude 
  Coll. 
  

  

  