Yol.  49.] 
A  MAMMALIAN  INCISOR  FROM  HASTINGS. 
281 
22.  On  a  Mammalian  Incisor  from  the  Wealden  of  Hastings.  By 
B.  Lydekker,  Esq.,  B.A.,  F.G.S.  (Bead  March  22nd,  1893.) 
Hitherto  the  only  evidence  of  the  existence  of  mammals  in  the 
English  Wealden  is  afforded  by  a  cheek-tooth  from  the  Wadhurst 
Clay  of  Hastings,  described  recently  by  Mr.  A.  Smith  Woodward,1 
and  referred  to  the  Purbeckian  genus  Plagiaulacc .  I  am  now, 
thanks  to  Sir  John  Evans,  K.C.B.,  in  a  position  to  affirm  the 
presence  of  a  second  mammal  in  the  same  formation,  which 
likewise  seems  to  be  referable  to  a  genus  originally  described  from 
the  Purbeck. 
The  specimen  on  which  this  determination  rests  is  an  apparently 
entire,  small  incisor  tooth  embedded  in  a  fragment  of  Tilgate  Grit. 
Sir  John  Evans  tells  me  that  he  found  the  specimen  in  a  block  of 
stone  at  Hastings,  in  or  about  the  year  1854,  and  that  he  presented 
it  to  Prof.  Prestwich,  by  whose  permission  it  is  to  be  now  transferred 
to  the  collection  at  the  Natural  History  Museum,  South  Kensington. 
The  rock  in  which  the  tooth  is  embedded  shows  some  signs  of 
having  formed  part  of  a  bone-bed,  although  there  are  in  it  no  other 
distinctly  recognizable  organic  remains. 
The  tooth,  of  which  figures  are  given  in  the  accompanying  cut 
(figs.  1,  1  a),  is  so  embedded  in  the  matrix  as  to  exhibit  only  the 
I.  la.  2.  2a. 
Figs.  1,  1  a.  Side  and  front  views  ot  a  mammalian  incisor  from  the  Tilgate 
Grit.  \  nat.  size. 
Figs.  2,  2  a.  Similar  views  of  an  incisor  of  Allodon ,  from  the  Jurassic  of 
North  America. 
front  edge  and  one  lateral  surface,  with  part  of  the  opposite  side. 
In  size  and  form  it  so  closely  resembles  an  incisor  tooth  of  a  rat, 
that  at  first  sight  it  might  be  taken  to  indicate  the  existence  of  a 
member  of  the  Bodentia  in  the  Wealden.  The  tooth  has  the  usual 
curved  form  of  a  Bodent  incisor,  and  exhibits  on  its  anterior  face  a 
thick  coating  of  enamel,  which  stops  abruptly  at  the  edge  of  the 
exposed  lateral  surface,  and  at  the  free  extremity  of  the  specimen 
is  likewise  seen  to  be  wanting  on  the  opposite  surface.  The  exposed 
lateral  surface  is  flattened,  while  the  opposite  one  is  somewhat  con¬ 
vex  and  bevelled  away ;  and  it  is  thus  evident  that  the  former  is  the 
1  Proc.  Zool.  Soc.  1891,  p.  585. 
Q.J.G.S.  No.  195. 
T7 
