Final answer:
The distal cusp of a lower first molar does not meet another cusp's triangular ridge to form a transverse ridge.
Step-by-step explanation:
In dentistry, when discussing the first molar, we're often concerned with its surface anatomy and the arrangement of its cusps and ridges. The five-cusp first molar typically has transverse ridges, which are formed by the union of two triangular ridges descending from the cusps adjacent to one another. However, certain cusps, like the distal cusp of a lower first molar, do not form a transverse ridge as they do not have an opposing cusp's triangular ridge to join with.