. A manual of zoology. Zoology. Fig. 523. Vjg. 524. Fig. 523.âHorizontal section through the anterior trunk region of a young RJimlnis amanis at the level of the Acnlral arclies. c, uolochonl: h, skin; //, ni\osc]ita: ;h, longitudinal nuiscles; r, rib end of the cartilaginous \'entral arch; â :â , osseous centrum. Fig. 524.âHorizontal section of an \o of Triton (from O. Hcrtwig). r/;, notochord,- uh, myoccele; i(i,primar)' segment (myotome). musculature. The development of an internal skeleton renders it neces- sar}' that the point of resistance of the muscles be transferred from
. A manual of zoology. Zoology. Fig. 523. Vjg. 524. Fig. 523.âHorizontal section through the anterior trunk region of a young RJimlnis amanis at the level of the Acnlral arclies. c, uolochonl: h, skin; //, ni\osc]ita: ;h, longitudinal nuiscles; r, rib end of the cartilaginous \'entral arch; â :â , osseous centrum. Fig. 524.âHorizontal section of an \o of Triton (from O. Hcrtwig). r/;, notochord,- uh, myoccele; i(i,primar)' segment (myotome). musculature. The development of an internal skeleton renders it neces- sar}' that the point of resistance of the muscles be transferred from the skin to the interior. A dermal musculature occurs only as an incon- spicuous remnant; it is replaced liy a body musculature. Idris latter consists primarily of a system of longitudinal muscle libres on either side of the verteliral column (fig. 52,;^), which are tlivided by connective-tissue partitions, the iiiyoscfyla, into successixe segments, the ))ivolo))ics. Thus when the eonnecti\e tissue of a lish is dissolved by cooking, the muscles fall into disk-like jiarts. The myosepta extend from skin to axial skeleton. Since they rim ol)li(|uel)' l)ackwards from the skeleton to the skin, they ser\e to render the skeleton a point of resistance for the action of the muscles. A segmented trunk musculature occurs in the IShxinoids (and in ), in which the axial skeleton consists only of notochord and is consequently unjointed. The segmentation of the muscles is therefore ohier than that of the skeleton and, as we can further say, is the cause of 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
