Joaquin G. Hidalgo (1839–1923) was a well-known Spanish malacologist who has published both on marine and non-marine shells. He had a focus on Spain and the Philippines, but during his early career also published on shells from the Neotropical area. Azpeitia (1923) has published his bibliography, list of new taxa described, and eponyms; he also published a portrait at unknown age (likely early 20th century).
Recently I was given the following portrait, which is dated 1882 .
Azpeitia F. 1923. El Doctor Hidalgo y sus publicaciones malacológicas. Revista de la Real Academia de Ciencias 21: 58–120.
 I am very grateful to Wim Backhuys, who presented me this copy from the Crosse archive.