Gnomes are a genus of hominids present in most planes adjacent to Spearbreakers. The most familiar species of this genus are the Mountain Gnome and Dark Gnome, which are present in nearly all planes in which gnomes evolved; though fairly intelligent, neither species possesses the mentual faculties to develop true civilisation.
However, there appears to be a third species of gnome (tentatively referred to as 'High Gnome' for the purpose of this document) which is not present on all worlds, which is capable of civilisation and technological advancement. The few known representatives of this third species include Mr Frog; due to a narrow sample population, it is difficult to make accurate statements regarding the general traits of the species as a whole. What has been seen indicates that high gnomes may be slightly taller than dwarves (albeit with a narrower frame and slimmer physique more in line with that of a human) and can possess an extremely-high degree of intelligence, albeit with lacking strength.
There has been speculation that high gnomes also possess a natural affinity for magic, particularly techniques which manipulate earth and stone; however, Mr Frog, the fortress's most prominent gnomish resident, has not yet demonstrated any special talent for magic of any variety, suggesting either that these speculations are false or, alternately, that Mr Frog is quite literally a magical retard, sitting on the far low end of the arcane bell curve for his species.