in natural history, the name of a genus of fossils of the class of septaria; the characters of which are, That they are bodies of a dusky hue; divided, by septa or partitions of a sparry matter, into several more or less regular portions; of a moderately firm texture; not giving fire with steel; but fermenting with acid menstrua, and easily calcining. The septariae of this genus are of all others the most common, and are what have been known by the little expressive or mistaken names of the waxen vein, or ludus Helmontii. We have many species of these bodies common among us. Of the whitish or brownish, we have thirteen; of the yellowish five; and of the ferruginous ones four.