Mr O enquires " What would science gain by the change" from the term Simiadce to Cebidce, as applied to the American species ? I answer, it would gain a term implying that the family contains the genus Cebus (which it does) instead of one implying that it contains the genus Simia (which it does not).

Mr O further writes " The very advantage of Sime- moria technical is entirely in favour of my nomenclature, and would be totally destroyed by the adoption of the very rule which Mr S.

Intends should secure it.

" This is, I think, rather too unqualified.

All candid persons will admit that when the term Cebidce is used to express the family which contains the genus Cebus, the advantages of a memoria tecli- nica are not totally destroyed.