44 EXTINCT MONSTERS. 
shoals of the fishes of those times, whose numbers were thus 
to some extent kept down. There is clear proof of this in the 
fossilised droppings—known as “coprolites,’—which show on 
examination the broken and comminuted remains of the little 
bony plates of ganoid fishes that we know were contemporaries 
of these reptiles. Probably young ones were sometimes devoured 
too. 
It was in the period of the Lias that fish-lizards attained to their 
greatest development, both in numbers and variety; and the 
strata of that period have preserved some interesting variations. 
It will be sufficient here to point out two, namely, Ichthyosaurus 
tenuirostris—an elegant little form, in which the jaws, instead of 
being massive and strong, were long and slender like a bird’s 
beak ; and also Ichthyosaurus latifrons (Fig. 5), with jaws still more 
Fic. 5.—Skull of Lehthyosaurus latifrons. 
birdlike. Our artist has attempted to show the former variety in 
our illustration (Plate II.). A most perfect example of this pretty 
little Ichthyosaur, from the Lower Lias of Street in Somerset, 
has recently been presented to the National Collection at South 
Kensington by Mr. Alfred Gillett, of Street, and may be seen 
there. In this group of fish-lizards the eyes are relatively larger, 
and we should imagine that they were very quick in detecting 
and catching their prey ; their paddles also have larger bones. 
There is a remarkably fine specimen at Burlington House, in 
the rooms of the Geological Society, of an Ichthyosaurus’ head, 
which the writer found, on measuring, to be about five feet six 
inches long. A cast of this head is exhibited at South Kensington. 
The largest of the specimens in the National Collection is twenty- 
two feet long and eight feet across the expanded paddles ; but it 
