51 
ment  aux  autres  espèces,  habite  le  Brésil, 
principalement  les  environs  de  Rio  de  Ja¬ 
neiro.  Nous  l’avons  recueillie  dans  les  ma¬ 
rais  de  S.  Christophe  où  elle  est  assez  rare. 
Son  animal,  blessé  rend  une  liqueur 
rougeâtre  sanguinolente.» 
The  observations  of  D'ORBIGNY  on 
the  Planorbis,  referred  by  him  to  ferrugineus 
SPIX,  can  not  apply  to  olivaceus  SP1X,  as 
the  dimensions  would  suggest.  Not  only 
is  olivaceus  never  found  in  Rio  (where  Schi- 
slosomurn  is  unknown)  but  the  species  still 
existing  in  São  Christovão  is  our  confusus 
(unable  to  transmití  the  parasite).  Its  largest 
specimens,  but  rarely  found  in  Manguinhos, 
are  very  like  olivaceus,  but  do  not  ex¬ 
ceed  25  mm. 
3.  Planorbis  (A/lenethes)  nigricans 
SPIX  1827. 
(Plate  15  fig,  3  a,  b,  c,  d.) 
Syn.  lugubris  WAGNER  1827 
Tenagophilus  D’ORBIGNY,  1847 
Biangulatus  Spec.  25  of  REEVE-SO- 
WERBY. 
By  the  rules  of  priority  SPIX’s  name 
seems  to  take  the  precedence  ;  according  to 
WAGNER,  he  gave  it  to  the  two  larger  of 
four  specimens  ;  the  two  others,  called  al¬ 
bicans  and  viridis,  were  voung  and  one  had 
lost  its  epiderm.  They  were  found  together 
with  olivaceus.  WAGNER,  despising  the 
name  of  SPIX,  gave  another  collective  name 
and  D’ORBIGNY,  much  later,  still  augmen¬ 
ted  the  synonymy,  without  any  necessity,  as 
he  must  have  known  the  work  of  SPIX  and 
WAGNER.  The  last  name,  tenagophilus,  is 
frequently  found  in  littérature.  There  is  not 
much  doubt  about  the  identity;  only  for  the 
species  of  other  american  countries  one 
might  desire  a  more  exact  comparison. 
I  give  drawings  of  chosen  specimens.  As  is 
the  rule,  the  majority  of  specimens  is 
not  of  the  largest  size,  with  a  shell  of 
about  18  mm.  in  diameter.  The  height  of 
the  whorls,  forming  the  principal  feature  of 
the  species,  is  rather  variable  and  may  at¬ 
tain  about  8  mm.  At  the  same  time,  the  width 
is  reduced  becoming  much  less  than  the 
height.  In  sinistra!  position,  the  upper  pari 
of  the  whorls  is  very  prominent  and  has  a 
rounded  keel.  Below  and  outside,  the  whorls 
have  another,  less  distinct  keel.  The  horny 
shell  shows  a  reddish  brown  colour,  more 
pronounced  than  in  other  species,  and  is,  so¬ 
metimes,  somewhat  opaque,  even  in  the  live 
animal.  The  pigmentation  of  the  animal  is 
a  little  variable,  but  generally  very  dark;  it  be¬ 
comes  velvety  black  over  the  respir  tory  ca¬ 
vity.  The  species  was  found  by  SPIX,  toge¬ 
ther  with  the  first  one,  in  the  State  of  Bahia 
from  where  I  received  tyoical  specimens, 
collected  in  Caravellas.  D’ORBIGNY  found 
it  in  the  Argentine  Republic;  it  also  exists 
in  Uruguay  (1)  and  Paraguay.  In  Rio  it  is 
not  rare.  I  got  typical  specimens  from  a 
ditch  in  Santa  Cruz,  where  it  was  the  only 
Planorbis.  In  Manguinhos  and  other  places 
it  is  found  together  with  the  preceeding 
species,  making  the  determination  of  some 
specimens  difficult,  because  both  the  species 
vary  and  only  the  typical  forms  are  easily 
distinguished,  while  the  aberrations  are  more 
alike.  1  give  a  reproduction  of  the  descrip¬ 
tions  of  SPIX  and  WAGNER  and  D’OR¬ 
BIGNY. 
SPIX  et  WAGNER,  pag.  27. 
“Planorbis  lugubris  WAGN.  Tab.  XVIII 
fig.  3,  4,  5,  6. 
Pi.  testa  discoidea,  tenui,  utrinque  pro¬ 
funde  umbilicata,  ferruginea  ;  anfractibus  ro- 
tundatis,  oblique  stratis. 
a)  Testa  adulta  maiore. 
b)  Testa  juniore,  minore:  Planorbis  ni¬ 
gricans,  albescens  et  viridis  SPIX,  Tab.  VXI11 
Fig.  3,  4,  5,  6. 
Chemnitz,  Conchylienkabinet,  Tom.  IX, 
Tab.  127,  Fig.  118. 
Testa  discoidea,  tenuis,  pellucida,  striis 
obliquis  numerosissimis,  subtilibus  instructa  ; 
epidermide  tenui  vestita.  Anfractus  quatuor 
rotundati  ;  ultimus  inflatus,  cylindricus  ;  cae- 
teri  gyri  utrinque  aream  profunde,  excavatam 
formantes,  quae  tamen  in  parte  inferiore  est 
1)  Specimens  of  Concordia  in  Uruguay,  though 
apparently-  of  the  same  species,  have  much  larger  dimen¬ 
sions  (22-23  and  8-9  mm.) 
