. A manual of elementary zoology . Zoology. THE LANCELET 329 General Anatomy, The skin is covered with a columnar epithelium, ciliated only within the oral hood and in parts of the atrium. The connective tissue is scanty, and consists of fibrillated ground substance with some cells. There is a thick muscular body-wall, divided, as we have seen, into segments, which are V-shaped and fit into one another so that several are cut in a transverse section. Within the body-wall lies a perivisceral ccelom, not A-f-'. est. Fig. 237.—Amphioxus, ph The forepart of the body cut in half longitudinal
. A manual of elementary zoology . Zoology. THE LANCELET 329 General Anatomy, The skin is covered with a columnar epithelium, ciliated only within the oral hood and in parts of the atrium. The connective tissue is scanty, and consists of fibrillated ground substance with some cells. There is a thick muscular body-wall, divided, as we have seen, into segments, which are V-shaped and fit into one another so that several are cut in a transverse section. Within the body-wall lies a perivisceral ccelom, not A-f-'. est. Fig. 237.—Amphioxus, ph The forepart of the body cut in half longitudinally. a/.,"Atrium; , atrial floor; , central canal of nerve cord; , cerebral vesicle; dorsal fin rays ; est., endostyle ; , nerve cord ; nch., notochord ; , oral cirri; , oral hood ; , peripharyngeal band ; pg., anterior pigment spot; pk., pharynx ; , skeleton of cirri; , skeleton ring in oral hood ; , velar tentacles; vm., velum ; ', part of wheel organ. divided by septa, but greatly complicated by the presence of the gill slits, which reduce it in the region of the pharynx to a number of canals presently to be described. There are numerous other ccelom ic cavities, of which the most important are those in the region in front of the mouth, in the velum, in the metapleural folds of the larva, and in the gonads. As in the frog, the dorsal body-wall is much thicker than the ventral. In it there lies a longitudinal, hollow central nervous system, comparable to that of the frog, but at the front end not enlarged into a brain, though. 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
