THE EARLY DEVELOPMENT OF THE CHICK 285 



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FIG. 114. Chick embryo with adjacent portion of area vasculosa, with thirty- 

 five pairs of somites (about seventy- two hours). Dorsal view. From Lillie 

 (Development of the Chick), a. a., 1, 2, 3, 4, First to fourth aortic arches; Am., 

 amnion; AT., branches of vitelline arteries; Atr., auricle; A.V., vitelline artery; 

 B.A., bulbus arteriosus; cere. Fl., cervical flexure; cr. FL, cranial flexure; D.C., 

 ductus Cuvieri; D.V., ductus venosus; Ep., epiphysis; Gn. V., ganglion of V 

 cranial nerve; Isth., isthmus; Jug., external jugular vein; Md., mandibular arch; 

 M.M., maxillo-mandibular branch of V cranial nerve; Myel., myelencephalon; 

 olf.P., olfactory pit; Ophth. ophthalmic branch of V cranial nerve; Ot., otocyst; 

 8.2, s.10, s.20, etc., second, tenth, twentieth, etc., somites; V., branches of the 

 vitelline veins; V.c.p., posterior cardinal vein; V.umb., umbilical vein; V.V., 

 vitelline vein; V.V.p., posterior vitelline vein; W.B., wing-bud. 



