nd and Western Europe.

[Illustration: Fig. 27.--Teeth of the duck-billed dinosaur
_Trachodon_. The dental magazine has been removed from the lower
jaw and is seen to consist of several close-set rows of numerous
small pencil-like teeth which are pushed up from beneath as they
wear off at the grinding surface.]

_Camptosaurus._ The American counterpart of the Iguanodons of Europe
was the _Camptosaurus_, nearly related and generally similar in
proportions but including mostly smaller species, and lacking some of
the peculiar features of the Old World genus. In the National Museum
at Washington, are mounted two skeletons of _Camptosaurus_, a large
and a small species, and in the American Museum a skeleton of a small
species. It suggests a large kangaroo in size and proportions, but the
three-toed feet, with hoof-like claws, the reptilian skull, loosely
put together, with lizard-like cheek teeth and turtle beak indicate a
near relative of the great _Iguanodon_.

_Thescelosaurus._ The Iguanodont family survived until the close of
the Age of Reptiles, with no great change in proportions or
characters. Its latest member is _Thescelosaurus_, a contemporary of
_Triceratops_. Partial skeletons of this animal are shown in the
Dinosaur Hall; a more complete one is in the National Museum.

FOOTNOTES:

[Footnote 15: Trachodont teeth never drop out, they are completely
consumed. Only in the Iguanodonts and Ceratopsia are they shed.--B.
Brown.]

CHAPTER VII.

THE BEAKED DINOSAURS (Continued).

B. THE DUCK BILLED DINOSAURS,--TRACHODON, SAUROLOPHUS, ETC.

_Sub-Order Ornithopoda; Family Trachodontidae._

These animals of the Upper Cretaceous are probably descended from the
Iguanodonts of an older period. But the long ages that intervened,
some millions of years, have brought about various changes in the
race, not so much in general proportions as in altering the form and
relations of various bones of skull and skeleton and perfecting their
adaptation to a somewhat different habit of life, so that they must be
regarded as descendants perhaps, but certainly rather distant
relatives, of the older group.

We know more about the Trachodonts than any other dinosaurs. For not
only are the skeletons more frequently found articulated, but parts of
the skin are not uncommonly preserved with them, and in one specimen
at least, so much of the skin is preserved that it may fairly be
called a "dinosaur mummy." This spe