250 



V. H. EDGEW()r;TJ[, 



branchio-maiidibularis. The middle portion of the first and 

 the whole of the second (below the Aulage of the trapezius) 

 branchial myotomes disappear. 



In 5 mm. embryos of the rabbit the upper ends of the first, 

 second, and third branchial myotomes separate from the parts 

 below, the upper end of the third grows backward in the 

 neck, and the ii])per end of the second backward to join that 



Text-fig. 6."). 



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of the third (Text-figs. 85, 86, 87) ; in 6 mm. embryos the 

 upper end of the first has groAvn back to that of the second. 

 The hind end of the primitive trapezius, thus formed from the 

 upper ends of all three branchial myotomes, reaches the 

 anterior limb area in 7 mm. embryos (Text-fig. 88) ; its dorsal 

 edge extends upwards in 7\ mm. embryos (Text-fig. 90), and 

 in mm. embryos it has divided into the trapezius and 



