The fact that the Scyphomedusae have a number of well-marked peculiarities of form and structure is not incompatible with placing them in the Hydrozoa as a distinct sub-class, contrasting sharply in many ways with the Hydromedusae.
Many of the clusters are of very irregular forms, either showing no well-marked centre of condensation, or else condensed in streams along certain lines.
In hand specimens they:often show a well-marked banding which is sometimes flat and parallel, but may be sinuous and occasionally is very irregular, resembling the pattern of damascened steel.
The last well-marked lowering of the land took place in the Pleistocene period, when it was accompanied by glacial conditions, through which the greater part of northern England and the Midlands was covered by ice; a state of things which led directly and indirectly to the deposition of those extensive boulder clays, sands and gravels which obscure so much of the older surface of the country in all but the southern counties.
The extreme north of Liberia is still for the most part a very well-watered country, covered with a rich vegetation, but there are said to be a few breaks that are rather stony and that have a very well-marked dry season in which the vegetation is a good deal burnt up. In the main Liberia is the forest country par excellence of West Africa, and although this region of dense forests overlaps the political frontiers of both Sierra Leone and the Ivory Coast, it is a feature of physical geography so nearly coincident with the actual frontiers of Liberia as to give this country special characteristics clearly marked in its existing fauna.
To the three geographical divisions correspond three well-marked ethnical groups - the Onas of the main island, the Yagans (Yahgans) of the south and the Alakalufs of the west.
The dog was of many varieties as early as the XIIth Dynasty, when the greyhound and turnspit and other well-marked forms are seen.
The county is divided centrally, from west to east, by the well-marked range of hills known as the North Downs, entering Kent from Surrey.
If the differences in stature and form are constant, there can be no question as to the right of the dwarf Congo elephant to rank as a well-marked local race; the only point for consideration being whether it should not be called a species.
These are the nymphs, destined to acquire wings; their body is more slender in outline, and at first they bear well-marked tubercles.