298 Henry Woodward — Da/ron of Life on the Earth. 



Here we take leave of our Eeptilian frieuds, and go on further 

 back in time, with only Fishes to remind us of " animals with bach- 

 bones." But swelling with the portents of future races, which shall 

 arise to call him ancestor, behold the giant Pterygotus — largest of 

 Palaeozoic Crustacea, rivalling in size even the existing Inachus 

 Kcempferi from Japan, and far more muscular. Doubtless, in his 

 day, both in the Upper Silurian and in the Devonian, he played an 

 important part, devouring all things which came in his way, both 

 old and new, living and putrid ; like the existing members of his 

 family, he had not a high stomach ! 



Still evidences of land ! Mr, Samuel Scudd«r, of Boston, has 

 described several Devonian Insects ; Dr. Dawson, of Montreal, Mr. 

 Baily, of the Irish Survey, the late Prof. Forbes, and others, have 

 described several Devonian land-plants. Corals, as in the Carboni- 

 ferous Limestone, were plentiful, and many formed reef-like masses 

 of great size and compactness. A peculiar form of Trilobite with 

 a large fan-tail {Bronteiis flabellifer) , and more Brachiopods. 



The fishes have a tendency to imitate King- Crabs ; their bucklers 

 are peculiarly Crustacean-looking — another case of mimicry : *vho 

 set the fashion ? and who followed ? 



Judging by the numbers of Trilobites and Crinoids, we have 

 reached the " Kingdom of Siluria," and behold the rich treasures of 

 the Wenlock Limestone, its stores of Brachiopoda, its oldest King- 

 Crab, Neolimulus falcatus, its queer Pterygoid, its Corals and earliest 

 remains of Fishes. But time would fail to tell in detail the fauna of 

 each rock of Ludlow, Wenlock, Woolhope, Llandovery, Caradoc and 

 Bala, Llandeilo and Arenig, each a world of ages in antiquity, but 

 still full of Crinoidea, Starfishes, Trilobites, and Lampshells, with 

 varied forms of Orthocerata. 



And now, wreathed in Graptolites, comes the Cambrian, with its 

 Slate-rocks, and more new Trilobites, a Starfish and a Crinoid, 

 Lingulas and Zoophytes. Again rock-mass succeeds to rock -mass : 

 Tremadoo-slates, Lingula-flags, Harlech-grits, Llanberis-slates. Is 

 this the last? No, emphatically. Logan in Canada has added 

 yet another conquest, and brought in the great Laurentian kingdom, 

 with its (as yet) single fossil, the Eozoon Canadense. 



What is this Eozoon Canadense ? This to us, at present, oldest 

 known form of life. 



I have already spoken of the "Nummulitic formation," a lime- 

 stone of Eocene Tertiary age, extending from England to China in 

 a broad band, and in thickness sufficient to help to build up the 

 Pyrenees, the Alps, the Atlas Mountains, the Carpathians, and even 

 the mountains of Asia, extending into China and Thibet. 



This limestone is made up largely (often entirely) of the lenticular 

 shells of Nummulites. Instead of shells, imagine it one shell, one 

 animal, and you have a notion of what Eozoon is like. 



I have told you of the Chalk, covering an area as large as Europe, 

 being largely composed of the shells of a microscopic Foraminifer 

 called Globigerina. Instead of many shells, imagine it one shell, and 

 you have a notion of what Eozoon is like. 



