318 



VERTEBRATE ZOOLOGY 



ce/v/7. - 



cr/7. 



FIG. 163. Chick embryo of 35 somites, drawn as a transparent object, a. a. 

 1,2,3, 4, First, second, third, and fourth aortic arches; Ar, artery; A. V, vitelline 

 artery; cerv. Fl, cervical flexure; cr. Fl, cranial flexure; D. C, duct of Cuvier; 

 Ep, epiphysis; On. 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 trigeminus; Ot, 

 otocyst; V, vein; W. 6, wing bud; V. C. p, posterior cardinal vein; V. umb, um- 

 bilical vein; V. V, vitelline vein; V. V. p, posterior vitelline vein. (From Lillie's 

 " Development of the Chick.") 



