. A manual of elementary zoology . Zoology. THE SWAN MUSSEL 323 which lie side by side in the foot, just above the muscular region, about one-third of the length of the organ from its front end. The pedal ganglia bear the same relation to the cerebral that the subpharyngeal do to the suprapharyngeal in the earthworm. The pedal ganglia give off several nerves to the foot, and each sends a nerve to a statocyst which lies shortly behind it. Each cerebral ganglion also gives off a visceral commissure, which runs backwards between the kidneys to join one of the visceral or parietosplanchnic ganglia
. A manual of elementary zoology . Zoology. THE SWAN MUSSEL 323 which lie side by side in the foot, just above the muscular region, about one-third of the length of the organ from its front end. The pedal ganglia bear the same relation to the cerebral that the subpharyngeal do to the suprapharyngeal in the earthworm. The pedal ganglia give off several nerves to the foot, and each sends a nerve to a statocyst which lies shortly behind it. Each cerebral ganglion also gives off a visceral commissure, which runs backwards between the kidneys to join one of the visceral or parietosplanchnic ganglia which lie as a fused pair on the. /b m, Fig. 231.—A glochidium larva in ventral view.—From Latter. 6., Byssus (cut short); d., future mouth ; m., adductor muscle ; sensory cells ; main teeth and denticles on ventral edge of each valve. under side of the posterior adductor muscle, immediately within the skin. The sense organs are inconspicuous. They include the statocysts, the tentacles of the ventral siphon, a sensory epithelium, believed to be olfactory, which covers the visceral ganglion and is known as the osphradium, and tactile nerve endings in various parts of the skin. There are no eyes. The sexes of the swan mussel are separate. Sperm is passed out through the dorsal siphon and y' spermatozoa are drawn into the females with the inward stream. The eggs are fertilised in the cloacal chamber and then passed into the space between the lamellae. 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 Borradaile, L. A. (Lancelot Alexander), 1872-1945. London : H. Frowde, Hodder & Stoughton
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1920
