It is very much to be regretted that the carelessness and indifference of ignorant workmen in quarries, clay-pits, and railway cuttings have sometimes been the cause of valuable fossils being broken up, and so lost for ever. Unless they are accustomed to the visits of fossil-collectors who will pay them liberally for their finds, the men will not take the trouble to preserve any bones they may come across in the course of their work. (An example of this negligence will be found on p. 95.) But when once they realise that such finds have what political economists call an "exchange value," or, in other words, can be turned into money, it is astonishing what zealous guardians of Nature's treasures they become! For this reason collectors often find what Professor Bonney calls the "silver hammer"--in other words, cash--more effective than the iron implement they carry with them. CHAPTER II. SEA-SCORPIONS. "And some rin up the hill and down dale, knapping the chucky stanes to pieces wi' hammers like sae many road-makers run daft. They say 'tis to see how the warld was made."--_St. Ronan's Well._ Our first group of monsters is taken from a tribe of armed warriors that lived in the seas of a very ancient period in the world's history. Like the crabs and lobsters inhabiting the coasts of Britain, they possessed a coat of armour, and jointed bodies, supplied with limbs for crawling, swimming, or seizing their prey. They were giants in their day, far eclipsing in size any of their relations that have lived on to the present time. Some of them, such as the Pterygotus (Fig. 1, p. 26), attained a length of nearly six feet. They belonged to the humbler ranks of life, and, if now living, would without doubt be assigned, by fishmongers ignorant of natural history, to that vague category of "shell-fish" in which they include crabs, lobsters, mussels, etc. These lobster-like creatures, though claiming no relationship with the higher ranks of animals, may well engage our attention, not only for their great size, but also for their strange build. [Illustration: Plate I. SEA-SCORPIONS. _Pterygotus anglicus._ _Eurypterus._ _Stylonurus._ Length 6 feet.] There are no living creatures quite like them. Certainly they are not true lobsters, and yet we may consider them to be first or second cousins of those ten-footed crustaceans[4] of the present day--lobsters, crabs, and shrimps, so welcome on the tables of both rich and poor. Some naturalists say that their nearest relations at the present day are the king-crabs inhabiting the China seas and the east coast of North America; and there certainly are some points of resemblance between them. Others say that they are related to scorpions, and for this reason we call them Sea-scorpions. (See Plate I.) [4] Crustaceans are a class of jointed creatures (articulate animals), possessing a hard shell or crust (Lat. _crusta_), which they cast periodically. They all breathe by gills.