158 The Official Guide to the 
gigantic club-mosses, many of them fifty or sixty feet — 
high. Calamttes were among the commonest forms of 
vegetation, being nothing more nor less than a huge 
Lquisetum or “horse’s tail,” similar to those growing 
in our ditches and on waste land. But they were of 
great height, some twenty or thirty feet. The ferns of 
‘this period were numerous, and the fronds of Spheno- 
pleris, Neuropterts, etc., are well preserved. 
“The Permian beds are to some extent represented 
by specimens from the Magnesian Limestone in Table 
Case 3. To the Permian formation belongs the fossil 
fish Palgontscus comptus, and from the Trias came the 
flagstones impressed with the hand-like footprints of 
Laby vinthodon or Chetrotherium. 
We now come to fossil remains from another series 
of rocks in Wall Cases 3, 4, and 5. The rocks from 
which most of these remains have come are known as 
Mesozoic or Secondary. ‘They comprise the ‘Trias, 
Lias, Oolite, and Chalk formations. Enormous in 
duration as was this secondary age, it was not one- 
third that of the Primary, if the comparative thickness 
of the two series be any criterion. This Secondary 
Age is speciaily that of Reptiles. ‘The Lias, which is 
proutic in fossils, has furnished the Museum with an 
abundance of remarkable examples. The most notice- 
able of these is the /chthyosaurus, discovered at Lyme 
Regis in 1811, and mounted in a frame in Wall Case 4, 
This is one of the marine Lizards, which, with paddles 
like a whaie and a jaw like that of a crocodile, was 
sometimes twenty feet long. ‘There are also portions ~ 
of the remains of these reptiles. One specimen is 
that of the head and jaws almost perfect. ‘The fish 
of the Liassic period are represented by the Dapedius 
(Wali Case 3), a broad form covered with bony 
enamelled plates instead of horny scales. 
Near these is a beautiful specimen of the “Stone 
