crenated

Unio fragilis is principally distinguished by the cardinal teeth: those in the right valves are 2; short, obtuse, and nearly obsolete, more resembling tubercles, than the crenated or striated teeth of this genus.

Bill elongated, thick, hollow, deflexed, the margins obtusely crenated, with excrescences of various forms placed on the upper mandible.

The specimen now before me is about the size of a magpie; the white collar only surrounds the back of the head, and is not well defined; the carinated process on the bill ends abruptly, and not gradually, as seen in Le Vaillant's figure; the margins are obtusely crenated, the tail even, and the two middle feathers entirely black.

Shell smooth, thick in the middle, brown, with a narrow whitish band; spire striated, the stri� with internal punctures: outer lip crenated; pillar 5 plaited.

Between these two genera should be placed another of Lamarck's, called by him Iridinia, which has likewise only a simple lamellar plate, but broken into a great number of crenated teeth.