Abstract
Larval, metamorphosing, and adult stages of Ichthyomyzon hubbsi were collected at several different times of the year from the Mills River and Bent Creek, two tributaries of the French Broad in North Carolina. Analysis of length-frequency data for ammocoetes, indicated that the duration of larval life is at least 5 ⅟4 and probably 6 ⅟4 years. The growth rate was most marked during the spring and summer and gradually decreases during larval life with little or no increase in length occurring in the year prior to metamorphosis. The external signs of metamorphosis first appeared in transforming animals between early August and the middle of September, and spawning took place in the following May or early June. The results are discussed in the context of estimates on the duration of the life cycle of paired species of lampreys.