Cromorne is the German "krummhorn;" there is no English equivalent known.    From Wordnik.com.  [Scientific American Supplement No. 819, September 12, 1891] Reference

100 musical instruments between them including clarinets, saxophones, flutes, guitars, banjos, mandolins, a hurdy-gurdy, bones, piccolo, accordions, a krummhorn, and a whole universe of other percussion, brass, stringed, and woodwind instruments.    From Wordnik.com.  [RutlandHerald.com] Reference