Excerpt from Bulletin No, 7 of the Illinois State Museum of Natural History: New and Interesting Species of Palæozoic Fossils

There are, therefore, thirty-three arms in this species. The arms are composed of a double series of interlocking plates that are deeper than wide in the lower part, but commence to spread, at the upper third, and become perfectly flat, in the upper part, as they do in Erelmocrinus, but without the usual increase in width. The plates of the arms do not seem to lengthen, but instead of closing, so as to have an ambulacral furrow on the inner side, they become perfectly flat on both sides, or concave externally. Pinnules dense.

There are three regular interradials in each area, one large, the other two small, but of unequal length. There are seven azygous interradials, the first one heptagonal, in line with the first primary radials, and of about the same size. It is followed by three plates, in the second range, the middle one being the longer and larger one. On each side of the upper part of the middle plate there is a small plate that separates it from the radial series. Above the middle plate of the second range, there is an elongated plate that extends an angle to the top of the calyx. The vault is not exposed, but it bears a long slender proboscis, the end of which is broken off at the top of the specimen illustrated.

This specie will be distinguished by its depressed calyx, and thirty-three arms or seventeen ambulacral orifices, in the vault, and by the flattening of the arms in the superior part. This latter character, in a greater degree, possibly, has been regarded as a generic character in Erelmocrinus. This species and others hereinafter described show that the flattening of the arms is not of generic importance. Many species of Balocrinus show the tendency of the arms to expand or flatten toward the superior ends.

Found in the Keokuk Group, at Boonville, Missouri, and now in the collection of S. A Miller.

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