Records of duplication of members in hexapod larvæ are so rare that I submit the subjoined account, drawn up from a specimen of the young of Corydalis cornuta, captured in the river near Iowa City, several years ago. The insect is one of a number that I took for class dissection, and as far as noted, the remainder did not depart from the ordinary type. A notice of the case was prepared at the time and sent to a scientific journal on the eve of its suspending publication, so that I think the article was never printed.