PLATES 



ABBREVIATIONS 



I-V, the five pharyngeal pouches 



1-6, the six aortic arches 



A. p., pulmonary artery 



A. p. a., pulmonary arch of mammals 



C. pb., postbranchial body 



Gl. pth. Ill, IV, parathyreoid out- 

 growths of the third and fourth 

 pouches 



Gl. th., thyreoid gland 



GL thy. Ill, IV, thymic outgrowths o' 

 the third and fourth pouches 



Hy., hypophj^sis 



P. d., P. s., right and left lung-buds 



S. c, cervical sinus 



St., mouth 



Tr, trachea 



X., transient vessel which lies medial 

 to the postbranchial body 



421 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 29, NO. 4 



