142 
MR.  BRODERIP'S  DESCRIPTIONS  OF  SOME  NEW  SPECIES  OF 
bisecting  it,  and  the  thickness  from  another  imaginary  line,  supposed  to  be  drawn 
through  the  middle  of  the  two  valves  and  the  included  space. 
Mr.  Cuming  found  this  Terebratula  in  the  Bay  of  Valparaiso,  at  a  depth  ranging  from 
sixty  to  ninety  fathoms.  The  older  shells  were  attached  to  rocks,  and  the  younger  to 
Corallines  and  Fuci. 
2.  Terebratula  Uva. 
Tab.  XXII.  Fig.  2. 
Ter.  testd  ovato-oblongd,  ventricosd,  subglabrd,  subdiaphand,  lineis  concentricis  substriatd ; 
valvd  perforatd  subelongatd. 
Long.  1  poll.,  lat.  f,  diam.  ^-V- 
Hab.  in  sinu  Tehuantepec. 
Mus.  Cuming. 
This  Terebratula  was  found  by  Captain  Dare,  while  dredging  for  Meleagrina  margari- 
tifera,  attached  to  a  dead  sea-worn  bivalve,  at  a  depth  of  from  ten  to  twelve  fathoms, 
and  on  a  bottom  of  sandy  mud. 
Genus.  Orbicula,  Cuv. 
1.  Orbicula  lamellosa. 
Tab.  XXIII.  Fig.  2. 
Orb.  testd  corned,  fused,  suborbiculari,  subdepressd,  lamellis  concentricis  elevatis  rugosd. 
Long.  ItV  poU.,  lat.  1. 
Hab.  ad  Peruvise  oras.    (Iquiqui. — Bay  of  Ancon.) 
Mus.  Cuming. 
This  species  was  found  by  Mr.  Cuming  in  groups,  the  individuals  being  in  many 
instances  piled  in  layers  one  over  the  other  on  a  sandy  bottom,  at  a  depth  ranging 
from  five  to  nine  fathoms.  At  Ancon  they  were  found  attached  to  dead  shells,  and 
also  clinging  to  the  wreck  of  a  Spanish  vessel  of  about  300  tons,  which  went  down  in  the 
Bay  about  twelve  years  ago.  The  sunken  timbers  (for  the  sheathing  was  gone  to  decay,) 
were  covered  with  these  shells,  much  in  the  same  way  that  beams  on  land  are  some- 
times invested  with  flat  parasitic  Fungi.  At  Iquiqui  they  w^ere  taken  adhering  to  a 
living  Mytilus. 
It  is  to  be  observed,  that  the  bearded  appearance  round  the  border  of  many  of  the 
specimens  is  produced  by  the  dried  remains  of  the  cilia  of  the  mantle.  The  lower  valve 
varies  very  much  according  to  circumstances,  being  thinnest  and  smoothest  when  it  is 
least  exposed :  in  those  instances  where  the  adhesion  is  co-extensive  with  the  surface, 
it  is  very  thin.  Generally  it  is  convex  where  it  rises  from  the  depressed  area  of  the 
perforated  part ;  but  this  convexity  depends  so  much  on  position  and  other  accidental 
circumstances,  that  it  cannot  be  relied  on  with  any  safety  as  a  character. 
The  measurement  merely  relates  to  the  extent  of  surface  of  the  upper  valve,  the 
