"In sultry forests / where apes swing to and fro"

In another Internet forum I mentioned our church's exclusive use of the 1940 Hymnal and got the following reply:

I learned to sing from the 1940 Hymnal. I miss it! Some funny hymns in there too...there's one in the "Missions" section (I think it was 262) with a line about people who work in "sultry forests where apes swing to and fro." Classic.

My immediate reaction (beyond "your church doesn't use the 1940 Hymnal?!") was: what is this hymn?

A little research said it's there, and it is in fact Hymn 262. Per another correspondent:

Remember all the people
Who live in far off lands
In strange and lovely cities
Or roam the desert sands,
Or farm the mountain pastures
Or till the endless plains
Where children wade through rice fields
And watch the camel trains.

Some work in sultry forests
Where apes swing to and fro,
Some fish in mighty rivers,
Some hunt across the snow.
Remember all God’s children,
Who yet have never Heard
The truth that comes from Jesus,
The glory of His Word.

God bless the men and women
Who serve Him overseas;
God raise up more to help them
To set the nations free,
Till all the distant people
In every foreign place
Shall understand His kingdom,
And come into His grace

Very English in some ways, but odd that I've never heard this. By my calculations if my church sang only one hymn each Sunday, in numerical order, by now I'd have sung each and every one three or four times. But this one.. never.

Then again there are other hymns I know I've never sung. Such as 468, Dies Irae, the favorite of an old friend, church organist and high-school chemistry teacher named Preston Q. Boomer. Looking at Dies Irae tonight we saw its "Part II" for the first time.

I wonder what else lurks in the unused forgotten corners of our Hymnal. Maybe Fr. Daniel can shed some light into those for us.