Lign. 175. Trilobites. Silurian Limestones.
| Fig. | 1.— | Illænus perovalis. (Murch. Sil. Syst.) |
| 2.— | Trinucleus Lloydii. (Murch. Sil. Syst.) | |
| 3.— | Calymene Blumenbachii: the upper surface of the carapace, viewed from above. Dudley. | |
| 4.— | The same, coiled up, and seen in profile. | |
| 4a.— | The same, seen in front. |
These fossils are the carapaces, or shells, of crustaceans, belonging to an extinct family,[469] which comprises many genera, and numerous species. Mortimer, Da Costa, Guettard, and Linnæus recognised the crustacean character of this interesting, but obscure class of organic remains: their true affinities, however, were first scientifically determined by Alex. Brongniart.[470] Many memoirs on the Trilobites have since been published by eminent Continental and American writers;[471] and much light has been thrown on the subject by the labours of Martin,[472] Parkinson, [473] Stokes, Phillips,[474] König,[475] Dr. Buckland,[476] Sir E. I. Murchison,[477] and others. The beautiful illustrations and interesting description of the Trilobites in Dr. Buckland’s Bridgewater Treatise (Bd. p. 389, and pl. xlv. xlvi.) must have rendered the reader familiar with the most important facts relating to these extinct beings; but subsequent discoveries have thrown additional light on their structure and natural affinities. The works of M. Burmeister,[478] Mr. Salter,[479] Prof M’Coy[480] and especially of M. Barrande,[481] should be carefully referred to by the student in this branch of Palæontology.
[469] The Trilobites appear to have been related more nearly to the Phyllopoda than to any other division of the Crustacea.
[470] Hist. Nat. Crust. Foss. Burmeister on Trilobites; Introduction.
[471] A Monograph on the Trilobites of North America, by Jacob Green, M.D. Philadelphia, 1832.
[472] Petrificata Derbiensia.