94 



R. H. WHITEHEAD AND J. A. WADDELL 



Fig. 1 PifT, 24 mm. Transverse section at level of ventral extremity of first 

 rib; rl, ventral extremity of first rib; sb, sternal band; 7na, median portion of ster- 

 nal anlage; pm, pectoral muscle. X 60. 



Fig. 2 Pig, 24 mm. Transverse section caudal to ventral extremity of^firgt 

 rjb; r/, first rib; -sb, sternal band; pm, pectoral muscle. X 60. 



