. The anatomy of the common squid, Loligo pealii, Lesueur. Squids; Mollusks. 31 cutting edge of the jaw. This edge is drawn up into a strong median tooth which is flanked by a pair of small notches. The pharyngeal muscles are attach- ed to the adjacent surfaces of the lamellae of each jaw and fill the narrow space between them. The jaws grow constantly by additions to their margin's and to their unexposed surfaces. They are marked by two sets of fine striae, the lines of growth, one set concentric with the point of the jaw and one set radiating from it. The jaws are brown- ish-black on the cut
. The anatomy of the common squid, Loligo pealii, Lesueur. Squids; Mollusks. 31 cutting edge of the jaw. This edge is drawn up into a strong median tooth which is flanked by a pair of small notches. The pharyngeal muscles are attach- ed to the adjacent surfaces of the lamellae of each jaw and fill the narrow space between them. The jaws grow constantly by additions to their margin's and to their unexposed surfaces. They are marked by two sets of fine striae, the lines of growth, one set concentric with the point of the jaw and one set radiating from it. The jaws are brown- ish-black on the cutting edges, amber colored near those edges, and colorless at the free margins. The upper mandible is almost as long as the pharynx and is shaped hke the prow of a very deep and narrow boat. Its inner lamella, to the dorsal end of which the oesophagus is attached, forms the greater portion of the lining of the oral cavity. The outer lamella is more strongly curved and is not half as large as the inner. The levator mandibuli is attached to its dorsal end. The lower mandible is about, half as long as the upper but is less compressed and more curved so that it fits over the distal end of the inner mandible. The inner lamella has much the same shape and size as the outer lamella of the upper jaw; the outer lamella of this jaw, is a long, broad band which extends backward parallel to the edge of the jaw and forms a pair of prominent wings, the alae. The upper jaw is comparatively fixed while the lower rotates thru an angle of 45° about an axis which passes almost thru the middle of each side of the inner lamella of the upper jaw. The muscular fibres (Text figure 11, c) which move the jaws arise from the inner lamella of the upper jaw and take a spiral course around this axis. The fibres (3 in the figure) from ,the lower portion of the middle of the inner lamella of the upper jaw pass directly outward and are inserted in a strong, superficial fascia which is attached to the outer lam
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmollusks, bookyear191
