336 



F. H. EDGEWORTH 



I am therefore of opinion that the evidences presented by 

 these embryos are sufficient to warrant a rejection of Greil's 

 statement that the branchial muscles are derived from down- 

 grbwths of the myotomes above, and to show that they 

 are derived from the lateral plates — as is usual in Verte- 

 brates. 



What is said above in relation to the first and second branchial 

 segments applies also to the third, fourth, and fifth. 



Text-fig. 10. 



4 bntnc/t. 

 tj Late/'o/ pi . 



K .j ~S S^^brcvnch. 



Late/^cU pt. 



Cells proUf. from. 

 epLth, . 



peric. per it. 

 duct 



larynx 



peruuxrcL. 



Embryo 11 mm., transverse section. 



Const rictores branchiales and Levatores ar- 

 cuum branchialium. — Both these muscles are developed 

 in the first four branchial arches, but a Levator only in the 

 fifth. Their anatomy in the adult stage was first described by 

 Jaquet (1897), and subsequently — with more accuracy — by 

 K. Fiirbringer (1904). Greil stated that the Levators in the 

 first four arches are developed from the upper part of the 

 mesoblast (i.e. myotome downgrowth) in the arches, whilst 

 the Constrictors are developed from cells given off from the 

 muscles at their upper and lower ends. His words are * welcher 

 jedoch keinen Rest des primaren den ganzen Bogen durch- 



