After the union of the Crowns the “British Seas” were very often referred to, and there was equal want of definition of their limits as in the case of the Sea of England. The advocates of the English claims to the sovereignty of the sea assigned them a wide but vague extent, while the Dutch argued that the British Sea was the Channel, the Mare Britannicum of Ptolemy and others, the North Sea being distinct and known as Oceanus Germanicus. In many of the diplomatic negotiations that took place on the subject there were heated discussions as to the meaning of the term the “British Seas,” and in point of fact the British representatives, like the Admiralty itself, were unable to define them. The only serious attempt which was made to define the Sea of England or the British Seas in relation to the claim to its sovereignty was made by Selden in 1635. It did not fail on the side of modesty, for according to him the Sea of England was “that which flows between England and the opposite shores and ports.”[13] More particularly in the opening chapter of his second book he describes the British Sea (Oceanus Britannicus) as being divided into four parts according to the four quarters of the world. On the west lay the Vergivian Sea, also called the Deucaledonian Sea where it washes the coasts of Scotland, and in which Ireland is placed; on the east is the German Ocean, so called by Ptolemy because it lies opposite the German shore; on the south, between England and France, is the sea especially noted by Ptolemy as the British Sea, the Mare Britannicum; but in reality all the sea extending along the shores of France through the Bay of Aquitaine (Bay of Biscay) as far as the northern coast of Spain was British. Since the northern and western ocean stretches to a great distance, to America, Iceland, and Greenland, and to parts unknown, it could not “all be called British,” but inasmuch as the King of Great Britain had very large rights in those seas, beyond the extent of the British name, it was not wholly to be left out of account. The indefiniteness of these boundaries to the north and west is obvious, but in a chart which he furnished, and which is reproduced in the frontispiece of this book, he presumably represented what he regarded as the British seas proper; and in several places in his work he expressly declared that the English sea and the English sovereignty of the sea extended to the opposite shores of the Continent.