TT #156 · Parshas Shemini · Aliyah 6 · Passuk 27
Chabad.org — Vayikra Chapter 11 with Rashi
English: And whatever walks on its paws among all the animals that walk on four legs shall be impure for you; whoever touches their carcass shall be impure until evening.
Sifra (Toras Kohanim), Shemini, Chapter 6.
Sefaria — Sifra, Shemini, Chapter 6
וְכֹל הוֹלֵךְ עַל כַּפָּיו. זֶה הַקּוֹף, כָּל הוֹלֵךְ – לְהָבִיא אֶת הַקּוֹפֵד וְאֶת חֻלְדַּת הַסְּנָאִים וְאֶת אַדְנֵי הַשָּׂדֶה וְאֶת כֶּלֶב הַיָּם.
Classification — The creature walking on its paws is identified as the monkey, while the broad wording adds related species.
The wording includes the listed creatures whose manner of walking is treated as walking on their palms.