. A manual of zoology. Zoology. 2 so CCELHEL:\nXTHES or spindle-sliapetl, circular in section. Tire mouth, at the extreme anterior cud, is either surrounded by a circle of tentacles (iig. 200), retracted together with the anterior end of the body by internal muscles, or is overhung by a dorsal preoral lobe or proboscis wliich may be several times the length of the liody and forked at its tip (lig. 26S). Internal segmentation is also lost, septa being entirely lacking. The nephridia are reduced in number, at most but three pairs being present, and in some but a single unpaired organ. They are t
. A manual of zoology. Zoology. 2 so CCELHEL:\nXTHES or spindle-sliapetl, circular in section. Tire mouth, at the extreme anterior cud, is either surrounded by a circle of tentacles (iig. 200), retracted together with the anterior end of the body by internal muscles, or is overhung by a dorsal preoral lobe or proboscis wliich may be several times the length of the liody and forked at its tip (lig. 26S). Internal segmentation is also lost, septa being entirely lacking. The nephridia are reduced in number, at most but three pairs being present, and in some but a single unpaired organ. They are the sexual (.iucts; the Chxtiferi have special excretory organs (tig. 26S, s;) covered with branching canals opening to the body cavity by nephrostomes and .1. Fio. :^6S.âFoiu'lliii vii'iJis. .1, fcmak- ^aftcr IIu\k-y); P, mak" (after SpoiifjclV r, cloaca; </, rudiiuentarv interline; ,c, cxcretor_\" organ; /, iiilcsline; m, niusck's SLii']torlini; inleslinc; 5, halls of spermatozoa in 5, in .4, proboscis (^'jreoral lobc^; ». single segnTci\tal organ,t'unctioningasoviductit'J, nephridium with ciliated funnel serving as vas deferens. emptying into the intestine. These resemble somewhat the branchial trees of the holothurians (infra), and hence the gephyra-a were formerly supposed to briilge the gap between holothurians and anueliils, whence the name {y(<tivpa, bridge). The vascular and ner\'ous systems are more like those of other anneliils. The vascular system consists of a sinus around the digestive tract and a dorsal and usually a ventral longitudinal trunk; the nervous system of a brain, cesophageal collar, and ^â ent^al cord,. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
