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 



FlG. 5. Skull of Ichthyosaurus lalijrons, 



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 



