54 
ment  over  the  breathing  cavity.  The  visceral 
part,  while  in  the  shell,  appears  rusty  brown. 
The  eves  are  middle-sized  and  the  an¬ 
tennae  rather  long  and  pointed.  The  foot  is 
short  and  the  shell  is  carried  parallel  to  the 
surface  on  which  the  animal  walks.  I  refer 
the  reader  to  the  drawings  distinctly  showing 
the  peculiar  characters. 
The  same  species  was  found  in  Bahia 
(Lagoa  da  Amaralinha)  and  in  the  city  of 
Natal.  Specimens  of  Planorbis  from  the  city 
of  Parahyba  (Lagoa  de  Baixo)  appear  some¬ 
what  larger  and  a  little  different;  they  belong 
to  the  following  closely  related  species. 
7  Planorbis  meileus  LUTZ 
(Plate  XVI  Fig  3  a,  b  c,  d). 
This  little  species  of  the  sub-genus  Spi- 
rulina  does  not  agree  with  any  found  in 
REEVE-SOWERBY,  nor  with  other  descrip¬ 
tions  in  the  literature  known  to  me.  Fom  PL 
heloicus  D’ORBIGNY,  it  is  easily  distinguished 
by  the  colour  of  the  animal,  and  from  Scg- 
mentina  janeirensis  CLESS1N  by  the  absence 
of  the  characters  of  this  genus. 
PI.  melleus  has  5  complete  whorls,  or  5 
V2  with  the  hollow  central  part.  Their  section 
is  asymmetrical,  sub-reniform,  without  a  keel, 
with  acute  internal  angles  only.  In  sinis¬ 
tra!  position  the  whorls  have  the  upper  part 
wider  and  the  upper  face  of  the  shell  more 
excavated.  The  calibre  of  the  whorls  increa¬ 
ses  very  slowly.  The  mouth  is  oblique,  some¬ 
what  sinuous  and,  sometimes,  a  little 
dilated  but  never  thickened.  Its  largest  dia¬ 
meter  is  oblique,  about  2  mm,  long  ;  the  last 
whorl  has  only  I  mm.  in  height  ;  the  lar¬ 
gest  diameter  of  the  shell  is  5  to  5  V2  mm. 
The  shell  is  amber  or  honey  coloured  ; 
in  life  the  largest  specimens  appear  ferrugi¬ 
nous  in  the  part  occupied  by  the  animal, 
which  has  long  antennae.  The  foot  is  long 
and  the  lanceolate  sole  ends  in  an  acute 
point,  while  the  cephalic  lobes  are  angular. 
The  general  colour  is  ocraceous-white  with 
black  markings  and  an  orange-yellow  stripe 
between  the  eyes,  which  are  very  large  and 
rimmed  with  white  principally  on  the  outside. 
The  animal  is  very  lively  and  graceful.  It 
likes  to  stretch  the  fore  part  very  much  out 
of  the  shell,  which  is  carried  horizontally. 
In  Rio  de  Janeiro  I  found  this  species 
in  pools  in  Manguinhos  and  Meyer,  also  at 
kilometer  22  of  the  Leopoldina  Railway,  in  a 
dirty  pool  without  water-plants.  In  Meyer  it 
was  found  between  green  algae  in  a  pool 
formed  by  inundation.  The  species  was  also 
discovered  in  Aracajú  and  near  the  salt¬ 
works  of  Parahyba.  This  snail  may  resist 
some  time  to  drought  by  burrowing  in  the 
mud.  It  is  not  very  rare  but  easily  escapes 
detection  owing  to  its  small  size  and  its 
tendency  to  hide. 
8-  Planorbis  (Taphius)  incertus  n.  sp. 
(Plate  XVII,  Fig.  9,  a,  b,  c,  10  d). 
I  was  unable  to  identify  this  small  spe¬ 
cies,  found  by  me  in  the  Capital  of  Parahy¬ 
ba  (Lagoa  de  Baixo)  and  in  Limoeiro,  state  of 
Pernambuco  (Lagoa  da  Estação).  Its  greatest 
width  is  abont  6,  its  greatest  height  aboui 
1  1/2  m  i.  It  has  four  whorls  or  4  V2  with 
the  hollow  central  part.  The  last  whorl  is 
deflected,  the  mouth  looking  upwards  but 
not  as  much  as  in  nigrilabris.  As  shown 
in  fig.  9  a,  the  mouth  is  more  angular  and 
the  lip  thinner.  No  black  rim  was  noticed. 
The  shell  is  transparent,  corneous  yellow, 
somewhat  opaque  and  whitish.  There  are 
spots  of  black  pigment  seen  in  the  extent  of 
about  one  circumvolution,  and  situated  in  the 
pallium  of  the  respiratory  cavity. 
9.  Planorbis  cimex  MORICAND  1837 
(Plate  XV11I,  fig.  14  a,  b). 
Original  description  : 
‘P.  testa  depressissima,  utrinque  leviter 
cóncava,  6 -volva,  ultimo  anfractu  subtus 
piano,  supra  semirotundato. 
Hab.  les  eaux  douces  aux  environs  de 
Bahia. 
Ce  petit  planorbe  n’a  que  six  millimètres 
de  diamètre,  et  un  millimètre  d’épaisseur.  Les 
tours,  au  nombre  de  six,  sont  très  serrés, 
plats  en-dessous  et  convexes  en  dessus, 
sans  carène  saillante  ;  mais  le  dernier  tour 
parait  caréné,  la  moitié  inférieure  étant  plate 
et  la  supérieure  bombée;  elles  forment  na- 
