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Fig. 5 Cat embryo, 18.5 mm. long. Cross section of junction of clavicles with 

 sternum. Princeton Embryological Collection, series 21, slide 13, section 2;c, 

 clavicle; s, sternum; x, connection between clavicle and sternum. X 60. ^ 



Fig. 6 Same embryo as in fig. 12. Slide 13, section 5. X 60. 



Fig. 7 Cat embryo, 12 mm. long. Princeton Embryological Collection, series 

 401, slide 10, section 24; r 1, tip of first rib: sb, sternal band; pm, pectoralmuscle; 

 pc, peri-cardial cavity; a, axilla. X 60. ^li -^ 



Fig. 8 Transverse section of sternal band and tip of second rib. Embryo no. 

 109, 10.5 mm. long, Mall collection. Slide 18, section 1, right side; r2, second rib; 

 sb, sternal band. X 250. 



101 



