Professor Brongniart places but little confidence in any of the generic characters above enumerated, except the number of articulations of the abdomen: these, however, in our opinion, are more vague and uncertain than most of the others. The genus, however, we think may be readily identified, after becoming familiar with one well characterized species. The general aspect of the buckler is peculiar—the body is not so depressed as in most other genera, and the lateral lobes are destitute of all membranaceous expansion.
To the genus Calymene, belongs the celebrated Dudley fossil, called Entomolithus paradoxus by Blumenbach, but which is not the same organic relic, to which Linné applied that name.
This genus includes a great number of species, and though some of them are said to be found in different and distant parts of the globe, they are according to our limited observation, for the most part confined, like recent species of animals, to particular districts. The C. polytoma, C. pulchella, C. bellatula, C. concinna, C. sclerops, and the C. punctata, all finely figured by Professor Dalman, and which are found in Sweden, have not yet been noticed in any part of North America.[12]
[12] See the valuable and extensive communication of J. W. Dalman, M. D., on the Trilobites, in the Transactions of the Swedish Academy for 1820, part 2d.
Calymene Blumenbachii. Brongniart. Cast No. 1.
Clypeo rotundato, tuberculis sex distinctis in fronte; oculis in genis emintissimis; corpore tuberculato.
In this species the upper lip presents a furrow parallel to its edges. The lip is straight. The cheeks are a little projecting. There are six rounded tubercles on the front, and fourteen articulations on the back; the tail is small, and the shell is covered with small rounded tubercles of unequal sizes.
The above is Professor Brongniart's description of this trilobite, which is the famous Dudley fossil described and figured by Littleton, in the Philosophical Transactions, (London) in 1750. According to Dalman, several distinct European species have been published under this name. The true C. Blumenbachii, he says, has thirteen articulations to the abdomen, and about eight to the tail. In the cabinet of G. W. Featherstonhaugh, Esq., we have examined a fine perfect specimen from Dudley,[13] in which there is fourteen abdominal joints. There can be no doubt, however, that several species have been confounded under the name of C. Blumenbachii; Dalman's C. Tuberculata and C. Pulchella are, we think, distinct from it, though he has marked them only as varieties.
[13] This famous trilobite, once formed a part of the cabinet of Mr. Parkinson, the distinguished author of the "Organic Remains," and is accurately figured on one of the plates of that splendid work. At the sale of the late Mr. Parkinson's fossils, it was purchased by Mr. Featherstonhaugh,
The true C. Blumenbachii, no doubt, abounds in North America, and is one of the few examples of the occurrence of an identical species on both continents. The late Abbe Correa sent a perfect specimen to Brongniart, from the vicinity of Lebanon, in the state of Ohio. We have also seen a number of specimens from that state, which could not be distinguished from the Dudley trilobite. Our model was taken from a specimen found at Trenton Falls, in the state of New York.