The Oldest Fossils (Lingula).—It is a noteworthy fact that these, the oldest fossil animals known, belong to species by no means low in the scale. Yet every trace of the many millions which must have preceded them, and have gradually led up to their development, have perished. The period of time which must have elapsed subsequent to the advent of life upon the planet and the development of the lingula mollusc was probably quite as long as that which has passed since the lingula left its shell in the mud of the Portmadoc slate. The oldest fossils which are known are found in the lower Cambrian rocks. They are small oval shells, which were, during life, the protection of small soft-bodied sea animals of highly complex structure: they had red blood. Their descendants are still found in great numbers burrowing in sand on the shores of tropical oceans. They have received the name of Lingula, and have in turn conferred that name on certain hard rocks in which their shells occur in abundance, the “Lingula flags” of Wales (Ray Lankester).
Huge Shark’s Teeth.—Ray Lankester figures, in his interesting lectures on extinct animals from which we have quoted the above a gigantic shark’s tooth. It is that of the Carharodon megalodon, and is three times the length of the tooth of any living shark. Specimens of this fossil tooth of smaller dimensions are common, and one should be found in every museum. They are obtained from the bone bed of the Red Crag at Felixstowe, but were not originally deposited in it. Many of them have fragments of a yet older sandstone adhering to them. Lankester calculates that his shark was 100 feet long.
THE GREAT FAMILY OF THE CAMELS AND DEER.
The Camel, the Camelopard, the Musk-deer and the Deer are all more or less nearly related. They constitute a branch of the great family of Ruminants, and all chew the cud. With the Camel are associated the Bactrian or two-humped Camel, the Alpaca, the Llama and the Vicuna. With the Giraffe we have the Okapi, and several extinct animals. The Musk-deer stands almost alone. Of Deer there are a great many species. It is easy enough to distinguish these various animals the one from the other when seen living in a Zoological Garden or stuffed in a museum. Indeed, at first sight, there might seem to be no great similarity between a Camel, a Giraffe, and a Fallow-deer. To the student of natural history, however, it becomes of great interest to observe the essential peculiarities of each. These may be grouped as those which prove relationship and those which show differences. We will leave aside the very important peculiarities in the stomach, because but few of our readers will have opportunities for examining them, and will confine our attention to the feet, horns, skull and teeth. All have two hoofs or more, and the Camel group have behind their hoofs a pad which covers the sole. None of them have hollow horns, and in none are their weapons of offence—horns, teeth, tusks, &c.—very effective. In all when adult the cutting teeth (incisors) in the upper jaw are absent, and in most the canines are either absent or much modified.
The Camel tribe differ from Giraffes in possessing a pad, and in having, when young, incisor teeth in the upper jaw, and fewer lower incisors by two. They have also strong canines in both jaws, no trace of horns, and nothing to be called tusks.
The Giraffes have two, three, or even five abortive horns of very peculiar development. They have very long necks, no pads, no tusks. The canine teeth in the lower jaw, which look like incisors, are much specialised in being cleft or notched.