108 Scientific Intelligence. 
: . 
extinct types ;—and the Cretaceous oy chalk-formation, comprisin 
the white chalk of the North and South Downs, and the chalk-marl, 
; basin, aboundiag in marine exuviee of special and for the most part 
this state the teeth resemble those of the living Iguana of the West - 
ndies,—a resemblance which suggested the generic name of Jguano- 
don. But the fossil teeth are of enormous size in comparison with 
more or less worn away by use, and the fang removed by absorption 
from the pressure induced by the upward growth of the successiona 
lique surface with a cutting edge on the summit, and the marginal cre- 
nations were worn away; in this state the fossil so strikingly resem- 
bled an upper tooth of a Rhinoceros, that Baron Cuvier pronounced te 
to belong to’a species of that genus. Numerous teeth in different 
ae 
