. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. TIIILOBITA. 483 fossil state, especially in the Solilenhofen lithographic slate, but also in older formations as far back as the Uebei-gangsgebirge (Cambrian, Silurian, etc.) formation. Llmnlus molncoanus Latr., East Indies. L. polijphcmus L., East Coast of North America. TRILOBITA.* In connection Math the Merostomata and the Xij^hosura, the Trilohites 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 hi
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. TIIILOBITA. 483 fossil state, especially in the Solilenhofen lithographic slate, but also in older formations as far back as the Uebei-gangsgebirge (Cambrian, Silurian, etc.) formation. Llmnlus molncoanus Latr., East Indies. L. polijphcmus L., East Coast of North America. TRILOBITA.* In connection Math the Merostomata and the Xij^hosura, the Trilohites 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 Fhyllopoda 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 Trilobiten," etc., Berlin, 1843. Beyrich, " Untersuchungen iibcr Trilobiten," Berlin, , 1840. J. Barrande, "Systcme silurien du centre de la ; Prasjue, S. W. Salter, " A monograph of the British Trilobites," London, 1864-1866. * Portions of appendages have been recently observed on the ventral surface of an Asaphns ("Notes on some Specimens of Lower Silurian Trilobites," by E. Billings ; also "Note on the Palpus and other appendages of Asaphus,"
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
