. A manual of zoology for the use of students : with a general introduction on the principles of zoology . Zoology. B'ig. 68.—Morphology of Trilobites. i. Angelitia Sedgvjickii; 2. Diagram of the cephalic shield of a Trilobite (after Salter), a Glabella; hb Free cheeks, bearing the eyes ipo); cc Fixed cheek, including the eye-lobe (rf); ee Facial suture. The cephalic shield of typical Trilobite is more or less completely semicircular (fig. 68, 2), and is composed of a central and of two lateral pieces, of which the two latter may, or may not, be united together in front of the former. The medi
. A manual of zoology for the use of students : with a general introduction on the principles of zoology . Zoology. B'ig. 68.—Morphology of Trilobites. i. Angelitia Sedgvjickii; 2. Diagram of the cephalic shield of a Trilobite (after Salter), a Glabella; hb Free cheeks, bearing the eyes ipo); cc Fixed cheek, including the eye-lobe (rf); ee Facial suture. The cephalic shield of typical Trilobite is more or less completely semicircular (fig. 68, 2), and is composed of a central and of two lateral pieces, of which the two latter may, or may not, be united together in front of the former. The median portion is usually elevated above the remainder of the cephalic shield, and is called the "glabella;" it protected the region of the stomach, and is usually divided into from three to four lobes by lateral grooves. At each side of the glabella, and continuous with it, is a small semicircular area, called the "fixed ; The glabella, with the " fixed cheeks " is separated from the lateral portions of the cephalic shield— termed th^ "movable" or "free cheeks"—by a peculiar suture or line of division, which is known as the '' facial suture," and is quite unknown amongst recent Crustacea, except for a faint indication in the Limulus, and more or less doubtful traces in certain other forms. The movable cheeks bear the eyes, which are generally crescentic or reniform in shape, are rarely pedunculated, and consist of an aggregation of facets covered by a thin cornea. The facial sutures may join one another in front of the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Nicholson, Henry Alleyne, 1844-1899. New York : D. Appleton
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