The organization of Trilobites, deduced from their living affinities. With a systematic review of the species hitherto described / By Hermann Burmeister ... Ed. from the German by Professor Bell ... and Professor E. Forbes.

  • Burmeister, Hermann, 1807-1892. Organisation der Trilobiten. English
Date:
1846
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Licence: Public Domain Mark

Credit: The organization of Trilobites, deduced from their living affinities. With a systematic review of the species hitherto described / By Hermann Burmeister ... Ed. from the German by Professor Bell ... and Professor E. Forbes. Source: Wellcome Collection.

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    than usual posteriorly, and is there furnished with a deep transverse furrow before the straight margin, and is drawn out at each side into three pointed marginal processes, which are situated lower than the general surface, and which issue from the deflexed margin. Locality.—The alumslate of Andrarum. Remarks.—]. Wahlenberg, who states that he has seen a perfectly preserved individual of this species at Copenhagen, describes it as having twelve body-rings with very short lateral lobes, which are pointed towards the posterior part; he has, however, represented the glabella and the caudal axis much too broad, and for this reason I am inclined to consider the body axis as also too broad. 2. Harlan (Med. and Phys. Rev. 400 et seq.) describes two new forms, nearly related to Par. scarabceoides. He speaks of them as Par ad. triarthrus (l. c. 401. 1, Fig. 5), and Par ad. arciiatus (l. c. 402. 2, Figs. 1, 2, 3). Both are from the carboniferous strata (?) of Utica, in New York. They are imperfect heads, which certainly resemble the fragments of 01. scarabceoides, but which still require a further investigation as to their true organization. The author compares them with Triarthrus Beckii (Green, Mon. 87, Fig. 6), with which they certainly seem to be related. 3. I shall treat more particularly in the Appendix of Triarthrus Beckii and Trilobites Sternbergi, which probably belong to the Oleneides. 4. I beg once more to remind my readers that I have mentioned Paradoxides spinulosus, Olenus forficula, and Olen. scarabceoides, as species which are both imperfectly known to me, and the correct arrangement of which in systematic order I cannot guarantee; this is still more the case with the other species of other authors, which I have only enumerated here hypothetically. GROUP THE SECOND. The lateral lobes of the body-rings not horizontally extended in their whole length, but turned downwards from the centre, and not terminating in a point, but with an arched and rounded extremity. Furrowed on the surface along their whole length. Camp ylo pleuri.* I am only perfectly acquainted with the first two of the three genera enumerated in this group; they are recognizable by their smaller, semilunar, cephalic shield, by their fewer number of joints (twelve to fourteen), and by their simple, semicircular, caudal shield. The one, Conocephalus, has fourteen rings; the other, Ellipsocephalus, twelve. The third genus, Harpes, has a very large cephalic shield, shaped like a horseshoe, with long posterior angles, and is stated to have twenty-eight rings. Genus 8.—Conocephalus, Zenker. Cephalic shield not unlike a half-moon, but the posterior internal margin only slightly bent. Glabella separated by a deep furrow from the lateral lobes, becoming more narrow towards the anterior payt, divided by four furrows at each side into four lobes, and becoming broader from the anterior to the posterior part; behind the fourth lobe there is a reflexed margin of articulation. The lateral parts, together with the cheek-shield, are highly convex, surrounded by a furrow and by a thickened margin. Eyes small, but certainly present; partly fixed at the anterior part beside the angles of the glabella, partly at the centre of the sides. * The following generic names, and the names of larger groups thence derived, have been already made use of to designate various tribes of Locusts.