File:Geological magazine (1883) (14785073313).jpg

Identifier: geologicalmagazi210wood (find matches)
Title: Geological magazine
Year: 1883 (1880s)
Authors: Woodward, Henry, 1832-1921, ed
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Publisher: London (etc.) Cambridge University Press
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

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tion attached to the neck lobe on either side.Eyes very large in proportion to head; reniform, smooth, but whenwell preserved showing a fine and minutely-faceted surface. Facialsuture uniting with outer border of free cheek, and forming a very 1 Messrs. Meek and Worthen, in their description of two Carboniferous Trilobitesfrom Illinois and Indiana, remark, eyes apparently smooth, but showing, when theouter crust is removed, numerous very minute lenses beneath, Geol. Surv. Illinois,vol. v., Paleontology, 1873, 4to. pp. 528, 529. This observation may serve toexplain the fact that many specimens do not show the faceted surface at all cleaily ;this is especially the case in the genus Griffithides. Emmrich believed it possible touse this character of the external surface of the eyes of Trilobites, as a means ofclassification, but I have not been able to accept his proposed arrangement based onthis structure. (See Emmrich, De Trilobitis ; Berlin, 8vo. 1839.) GeoLM.ag.1885. DecUeliyoLX.PlXI.
Text Appearing After Image:
&HWo odvavd - 3 cl - CarJboni teroas Triiobites.ThililpsicL . • xCc.3>Tioto-)itb.etrmjo. Carboniferous Limestone Trilobites. 449 acute angle, where it joins the glabella in front and a less acuteangle behind the eye, where it unites with the posterior border.A broad groove or furrow surrounds the free cheek, running exactlyparallel to its own outer border : the posterior angles of the headproject slightly backwards, but are not produced into cheek-spines.The incurved under margin of the shield is finely striated as well aspunctated. The hypostome (seen in situ in one of our specimens)is large, the mesial lobe is broad and spatulate, the surface beingfinely striated with wavy longitudinal lines; the lateral lobes oralte are small, smooth, and pointed. The thorax, which is roundly arched, consists of nine smooth andwell-defined segments, the first only having a minute tubercle onthe centre. The axis of the thorax, which next the head is con-siderably broader than its side lobes

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