Is the "Darwin-Marx correspondence" authentic?

From: Annals of science. 1975, vol. 32, no 1.

Bibliographic Details
Institution:International Institute of Social History
Format: TEXT
Published: N.pl., 1975.
Subjects:
Online Access:http://hdl.handle.net/10622/F7E54656-26A3-45AE-B23C-A50BFCFC0506
Description
Summary:From: Annals of science. 1975, vol. 32, no 1.
Published:1975.