. Elementary text-book of zoology. Zoology. TKILOBITA. 483 Ge. fossil state, especially in the Sohleiihofen lithographic slate, but also in older formations as far back as the Uebergangsgebirge (Cambrian, Silurian, etc.) formation. Lhinilux mdliicciiiuix East Indies. L. polypJtRinux L., East Coast of North America. TRILOBITA.* In connection with the Merostomata and the Xiphostira, the Trilobites may be considered. Their systematic position cannot as yet be defined with certainty. They lived only in the most an- cient periods of the earth's his- tory, and their fossil remains are found i
. Elementary text-book of zoology. Zoology. TKILOBITA. 483 Ge. fossil state, especially in the Sohleiihofen lithographic slate, but also in older formations as far back as the Uebergangsgebirge (Cambrian, Silurian, etc.) formation. Lhinilux mdliicciiiuix East Indies. L. polypJtRinux L., East Coast of North America. TRILOBITA.* In connection with the Merostomata and the Xiphostira, the Trilobites may be considered. Their systematic position cannot as yet be defined with certainty. They lived only in the most an- cient periods of the earth's his- tory, and their fossil remains are found in great numbers and are excellently preserved; but, un- fortunately, the conditions under which they were fossilised were such that the under side of the body, and, consequently, the structure of the appendages, that is the very characters which would enable us to decide their affinities, remain unknown to us. We may probably infer from this absence of any trace of appendages * in the fossils, that the legs were soft and delicate: but Burmeister's conclusion that they resembled the legs of the PhyUopoda is not justified. The body, which is frequently found rolled up, is covered with a thick shell, which is divided by two parallel longitudinal furrows into an elevated median portion (rhachis) and two lateral portions (pleura): it rarely attains any considerable size. There is an * Burmeister, "Die Organisation der ; etc., Berlin, 1843. Beyrich, "Untersuchuugen iiber Trilobiteu," Berlin, 1S45. 184(1. J. Barrande. "Systems silurien du centre de la Boheme," Prague, 1852. S. "\V. Salter. " A monograph of the British Trilobites,'' London, 1864-1866. * Portions of appendages have been recently observed on the ventral surface of an Axaplnix ("Notes on some Specimens of Lower Silurian Trilobites," by E. Billings ; also " Note on the Palpus and other appendages of Asapliu-," etc., by H. Woodward, Quart. Jnurn. of tin-
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
