Early keyboards: Saint Cecilia

This is Saint Cecilia, patron saint of music, as she was represented by Nicolas Poussin in 1628.
A few weeks ago I had a chance to visit the Prado museum in Madrid and there she was, playing the harpsichord among the cherubs. I could not resist the urge and took a picture with my phone (apologies for the low quality).

I believe that Poussin modelled his drawing after a real musician (look at the way she flexes her fingers and the position of the wrists) but I cannot say what kind of keyboard instrument is portrayed here. The shape of the frame seems reversed with the bentside on the left, and the compass covers about 3 octaves, maybe from C to c'''. Note the lack of external case. I read somewhere that this harpsichord is a double manual, anyway only one is represented. Interestingly enough when Raphael represented Saint Cecilia about one century earlier, he placed in her hands a small portative organ, with an odd reversed shape again: the longer pipes are to the right, and there is no evidence of bellows.