Dulcimer
The dulcimer (psaltery) consists of a wooden box with sound holes and several strings streched and aligned along the instrument's body. Although you can find dulcimers in many shapes, often it has a trapezoid format.
Cítara (a kind of psaltery)
How does it work?
The instrument is placed on a table or on musicians' legs, who plays the strings with his fingers or with a pick.
A bit of history...
The psaltery's origin goes back to 300 a.C., but it was popular mainly between 12th to 15th centuries. After 16th century, other instruments had origin from psaltery: the dulcimer, when played on a fretboard, and the harpsichord when connected to a keyboard and a mechanism plucks the strings.
Ancient psaltery' strings were made of animal guts, nowadays being substituted with metal strings.
Although the ancient psaltery did not have significant structural modifications, it is still played today in ancient music groups.
Psalteries have been built in Rio de Janeiro since 18th century. Curiously, four instruments built by Antônio Martins Santiago have survived till today: two psalteries can be seen in Brazilian museums (the one portrayed in the first picture is in Petropolis Imperial Museum), and two others in Portuguese museums.