Pul .. 



12 



14 15 



Fig. 9 The aortic arches of t he left side of an 8.5 mm. pig. (The development of 

 the rudimentary vessel seems to have been impeded by the common base of the 

 glandulethyroidicnne and the pre-pulmonic caecum). 



Fig. 10 The left fourth and pulmonic arches of the S.6 mm. pig. No. 78.Sof 

 the C. H. Spurgeon collection. (No attempt was made to illustrate these condi- 

 tions in figs. 6 and 7.) 



Fig. 11 Aortic arches of the right side of a 9.5 mm. pig, showing irregular con- 

 ditions. 



Fig. 12 Aortic arches of the right side of a 10 nun. pig, showing unusual condi- 

 tions. 



Fig. 13 The fourth and pulmonic arches of the right side of a 10 mm. pig, showing 

 the connection between the base of the pulmonic and the dorsal part of the fourth. 

 (Conditions similar to this were observed in three instances). 



Fig. 14. The fourth and pulmonic arches of a 9. (> nun. |)ig, showing a broad con- 

 nection between the dorsal portions. 



Fig. 15 The fourth arch of a 6.5 mm. ])ig, showing a division of that vessel on 

 its anterior face. 



513 



