A treatise on zoology . sforming a continuous series with ordinary trunk-muscles (Koltzoff[272], Hatschek [202]), in the Gnathostomes the myotomes of?the first tAvo or more metaotic somites vanish during ontogeny, andthe 4th somite (1st metaotic)^ never forms muscle even in theembryo (Figs. 2 and 3). ^ Many authors, Dolini, Kilian, Piatt, Sewertzoft, etc., consider that there arehere two or more fused somites; but the evidence, especially of the nerves, seems tobe against tliis view. HEAD SEGMENTS A varying number of somites behind the 6th grow downwardsand inwards to form the epibranchial and
A treatise on zoology . sforming a continuous series with ordinary trunk-muscles (Koltzoff[272], Hatschek [202]), in the Gnathostomes the myotomes of?the first tAvo or more metaotic somites vanish during ontogeny, andthe 4th somite (1st metaotic)^ never forms muscle even in theembryo (Figs. 2 and 3). ^ Many authors, Dolini, Kilian, Piatt, Sewertzoft, etc., consider that there arehere two or more fused somites; but the evidence, especially of the nerves, seems tobe against tliis view. HEAD SEGMENTS A varying number of somites behind the 6th grow downwardsand inwards to form the epibranchial and hypobranchial muscles,the dorsal myotome dwindling aAvay. A normal muscular segment,serial with the trunk-myotomes, is generally not developed at allin the head-region of a Gnathostome. The anterior mesoblastic somites extend downwards to form thelateral plate, which passes between or is pierced by the this plate are developed the muscles of the visceral skeleton A. t> p< t t: ad 0 V cb. Mr.
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
