Searching through my notes on these occurrences I found that I made two more sightings of alien species some time ago and never documented either specie.
Atheleni
“The Atheleni in Natures lottery had been luckier than most – and yet had missed one of the greatest prizes of all. They had powerful bodies and powerful minds, and they lived in a world which was both temperate and fertile. By human standards, they would have seemed strange but no means repulsive. Their sleek fur covered bodies tapered to a single giant rear limb that could send them leaping over the ground in thirty-foot bounds. The two forelimbs were much smaller and served merely for support and steadying. They ended in pointed hoofs that could be deadly in combat, but had no other useful purpose.”
Philens
"The Philen were little creatures, scarcely half the height of the Atheleni and did not hop, they rather walked upon two jointed limbs that seemed very thin and feeble. Fro the other appendages they processed multiple tentacles that they seemed to use very ambidextrousnessley. Its large spherical head was dominated by three huge eyes, set far apart and were capable of independent movement."
Second Dawn, Expedition to Earth, Arthur C. Clarke
I envisioned the Atheleni as being more like a rabbit than a horse.