. Outlines of zoology. loped,but there is a supra-ossophageal gangli-onic commissure from which the visceraland pedal cords extend backwards alongthe whole length of the body. There areno special sense organs on the head,which is but slightly differentiated ; butthe pallial sense organs are usually numer-ous and varied. A twisted gut runsthrough the body, surrounded by a diffusedigestive gland. There is a radula in themouth. The heart is median and pos-terior, and consists of a ventricle andtwo to eight auricles. There are twosymmetrical nephridia opening posteriorly,and consisting of much - b

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. Outlines of zoology. loped,but there is a supra-ossophageal gangli-onic commissure from which the visceraland pedal cords extend backwards alongthe whole length of the body. There areno special sense organs on the head,which is but slightly differentiated ; butthe pallial sense organs are usually numer-ous and varied. A twisted gut runsthrough the body, surrounded by a diffusedigestive gland. There is a radula in themouth. The heart is median and pos-terior, and consists of a ventricle andtwo to eight auricles. There are twosymmetrical nephridia opening posteriorly,and consisting of much - b Stock Photo
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https://www.alamy.com/licenses-and-pricing/?v=1 https://www.alamy.com/outlines-of-zoology-lopedbut-there-is-a-supra-ossophageal-gangli-onic-commissure-from-which-the-visceraland-pedal-cords-extend-backwards-alongthe-whole-length-of-the-body-there-areno-special-sense-organs-on-the-headwhich-is-but-slightly-differentiated-butthe-pallial-sense-organs-are-usually-numer-ous-and-varied-a-twisted-gut-runsthrough-the-body-surrounded-by-a-diffusedigestive-gland-there-is-a-radula-in-themouth-the-heart-is-median-and-pos-terior-and-consists-of-a-ventricle-andtwo-to-eight-auricles-there-are-twosymmetrical-nephridia-opening-posteriorlyand-consisting-of-much-b-image337143085.html
. Outlines of zoology. loped,but there is a supra-ossophageal gangli-onic commissure from which the visceraland pedal cords extend backwards alongthe whole length of the body. There areno special sense organs on the head,which is but slightly differentiated ; butthe pallial sense organs are usually numer-ous and varied. A twisted gut runsthrough the body, surrounded by a diffusedigestive gland. There is a radula in themouth. The heart is median and pos-terior, and consists of a ventricle andtwo to eight auricles. There are twosymmetrical nephridia opening posteriorly,and consisting of much - b
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. Outlines of zoology. loped,but there is a supra-ossophageal gangli-onic commissure from which the visceraland pedal cords extend backwards alongthe whole length of the body. There areno special sense organs on the head,which is but slightly differentiated ; butthe pallial sense organs are usually numer-ous and varied. A twisted gut runsthrough the body, surrounded by a diffusedigestive gland. There is a radula in themouth. The heart is median and pos-terior, and consists of a ventricle andtwo to eight auricles. There are twosymmetrical nephridia opening posteriorly,and consisting of much - branched tubes.The sexes are separate; a single repro-ductive organ extends dorsally betweengut and aorta almost the whole lengthof the body; the genital ducts are pairedand open posteriorly in front of theexcretory apertures. The ova, withchitinous spiny shells, are usually re-tained for some time by the female be-tween the mantle and the gills. The, segmentation is holoblastic, and a gastrulais formed by invagination.. Fig. 227.—Dorsal viewof nervous system ofAcanthochiton. —AfterPelseneer. I, Upper buccal commissure; 2, upper buccal ganglion ; 3, stomatogastric commis-sure; 4, labial commissure;5, sub-radular ganglia; 6,anterior pedal commissure;7, pedal nerve with pallio-pedal connections ; 8,supra-rectal pallial com-missure; 9, pallial nerve;zo, anastomosis of branchesof pedal nerves; iT,stomato-gastric ganglia ; 12, oeso-phageal nerves; 13,cerebral,commissure. GASTEROPODA. 419