206 



THE DEVELOPMENT OF THE CHICK 



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FIG. 117. Entire embryo of 35 s, drawn as a transparent object, 

 a. a. 1, 2, 3, 4, First, second, third, and fourth aortic arches. AT., 

 Artery. A. V., Vitelline artery, cerv. Fl., Cervical flexure, cr. FL, 

 Cranial flexure. D. C., Duct of Cuvier. D. V., Ductus venosus. 

 Ep., Epiphysis. Gn. V., Ganglion of trigeminus. Isth., Isthmus. 

 Jug. ex., External jugular vein. Md., Mandibular arch. M. M., 

 Maxillo-mandibular branch of the trigeminus. olf. P., Olfactory pit. 

 Ophth., Ophthalmic branch of the trigeminus. Ot., otocyst. V., 

 vein. W. R, Wing bud. V. c. p., Posterior cardinal vein. V. 

 umb., Umbilical vein. V. V., Vitelline vein. V. V. p., Posterior vitel- 

 line vein. 



