The Collaborative International Dictionary
Jacchus
Jacchus \Jac"chus\, n. [NL., fr. L. Jacchus a mystic name of Bacchus, Gr. ?.] (Zo["o]l.) The common marmoset ( Hapale vulgaris). Formerly, the name was also applied to other species of the same genus.
Wiktionary
jacchus
n. The marmoset (''Hapale vulgaris'')