On British Fossil Lepadidæ

Abstract

Abstract M r . D arwin noticed that great confusion exists in the nomenclature of the comparatively few species of Cirrhipeds, hitherto found in a fossil state; arising both from the easy separation of the several dissimilar valves soon after the death of the animal, and from the imperfect characters afforded by the valves themselves, which are, as it were, but parts of the crustacean carapace, neither accompanied with, nor distinctly impressed by, any of the soft parts of the animal. He then pointed out such particular valves as were sufficiently distinct, and had sufficiently constant characters to he considered as characteristic of genera,–as, for instance, the keel, or dorsal, valve in Sealpellum , and the scutal, or inferior lateral, valve in Pollicipes . The pedunculated cirrhipeds ( Lepadidœ ) were stated to have made their first appearance in the lower oolite, and to have reached their culminant point in the cretaceous epoch. The absence of sessile cirrhipeds in the earlier and secondary formations, and their occurrence for the first time in the eocene deposits, were then noticed, the author dwelling on the characters of the genus Verruca , and pointing out that, as the type of a group intermediate between, and of equal value with, the sessile and the pedunculate cirrhipeds, it offered no real exception to the rule that sessile cirrhipeds do not occur in the secondary formations; but that, on the contrary, it harmonizes with the law of relation between serial affinities of animals and their first appearance on this earth. Mr. Darwin concluded with a few observations on the comparative ranges of recent and fossil eirrhipeds, and on the close affinities between the extinct and the living forms.