In  the  ophidian  reptiles,  as  in  fishes  and  birds,  the  urinary
bladder  is  very  rarely  developed,  and  the  ureters  terminate
as  usual,  directly  and  separately  in  the  cloaca.  The  kidneys
of  serpents,  like  most  other  organs  of  the  body,  partake  of
the  elongated  form  of  the  trunk;  the  left  is  situated  farther
backwards  than  the  right ;  they  are  surrounded  entirely  with


EXCRETING    ORGANS.  631

peritoneum,  and  suspended  freely  in  the  cavity  of  the  abdo-
men, to  allow  of  greater  motion  of  the  vertebral  column  with
safety,  where  there  is  yet  no  fixed  sacrum.  They  have  a
deeply  lobulated  or  folded  structure,  consisting  of  a  long
series  of  flat  imbricated  tortuous  transverse  lobes,  or  regular
sinuous  folds  of  their  exterior  tubulated  portions,  resembling
externally  so  many  small  kidneys  pressed  closely  together.
The  contorted  and  convoluted  tubuli  composing  each  of
these  lobes,  pour  their  thick  white  viscid  secretion,  consist-
ing chiefly  of  uric  acid,  by  a  single  orifice  into  the  common
ureter,  without  forming  a  pelvic  enlargement,  and  without
the  calices  developed  in  the  more  concentrated  forms  of  the
kidneys  of  mammalia.
The  narrow  tubular  ureters  follow  along  the  inner  margin  of
the  kidneys,  receiving  successively  the  short  wide  common
ducts  of  all  the  separate  lobes,  and  open  by  distinct   orifices
into  the  back  part  of  the  cloaca,  as  in  other  oviparous  ver-
tebrata,  whether    provided  with,  or    destitute   of,  a  urinary
bladder;    sometimes,    however,  a  small    vesicular  dilatation
is  formed  on  each  ureter  before  it  opens  into  the   cloaca.
The  blood-vessels  penetrate  from  the  exterior  of  the  kidneys
between  the  lobes,  and  appear  to  have  been  mistaken  by
Huschke  for  tubuli  uriniferi  ramifying  through  the  lobes.
