The authority of Professor Brongniart is sufficient to place the C. Macrophthalma among the species of the United States, though we have been unable fully to identify it with his description.[22] He received a specimen, transformed into red jasper, from Prof. Ducatel, said to be found in the United States--no precise locality is given. Our model represents the animal which is supposed to be the one intended by Brongniart as the C. Macrophthalma of North America. It is, in our opinion, a variety of the C. Bufo. There can be no doubt that several species have been confounded under the name of C. Macrophthalma. [Footnote 22: We have seen in the Cabinet of Mr. Featherstonhaugh, a fine group of trilobites, in the transition limestone, from Dudley, (Eng.) Among them there is a perfect head, which agrees exactly with the description given by Mr. Brongniart of the head of his Calymene Macrophthalma. If this belongs to the true macrophthalma, our species under that name is entirely distinct. Since our work had been prepared for the press, Dr. J. J. Cohen, of the Baltimore College, has shown us the fragment of a calymene from Berkley, Virginia, which agrees with Brongniart's description of the macrophthalma, and with the above fossil from Dudley. We regret that the imperfection of the fossil prevents our giving a satisfactory cast of it.] The following extract of a letter from Professor Ducatel to the author, referring to the locality of this species, will be read with interest. "I cannot be positive as to my recollection of the locality of the fossil referred to by Brongniart and yourself, but believe it is one of several found by my friend Dr. M'Culloh, in the neighbourhood of Berkley Springs, Virginia. I regret that I have not in my possession another specimen to present to you." Calymene Bufo. _Green._ Cast No. 10. Clypeo rotundato, convexo, punctato; abdominis articulis sexdecim; cauda attenuata; corpore plano. Buckler semilunate, front very large, rounded before and arcuated at the insertion of the middle lobe; surface convex, and marked with numerous depressed pimples. Mouth large, lunate, resembling that of a toad or frog, with a narrow raised rim on the upper and under lip. Below the chin there are no pustulations. Cheeks small, triangular, and separated from the front by a deep, rectilinear furrow; the eyes in our specimen are much injured, but they are large, and near the upper angle of the cheeks. Middle lobe with a series of distinct double articulations. Lateral lobes wider than the middle lobe, ribs deeply grooved near their insertion; articulations of the abdomen twelve; of the tail ten. Length four inches and a half; breadth of the buckler nearly two inches.