I just went to another Lenten concert, and this week the "specialty of the day" was a pair of corni da caccia (which I hope the program spelled correctly as corno da caccia singular and that I guessed that corni is the plural). I had not been familiar with this instrument. If I had been listening to a recording without knowing what they were, I'd have said they were French horns playing high notes. Here is a picture of one:
image

The program said that they are hunting horns, and further that these two (played by a U of L faculty member and a graduate student) were the only pair in the United States. Frankly, I find this a little hard to believe. Are they really that rare? I can say they certainly were not a matched pair: one was obviously older, with a burnished-but-dull well, brass color; the other was bright-and-shiny new, nearly a white-metallic color.

FTR, there were also a French horn, a Fluegelhorn, a violin, and an organ.