320 



COMPARATIVE ANATOMY 



the embryo. In the region of the pharynx the splanchnic layers of meso- 

 derm unite in the median plane to form the tubular heart and the meso- 

 cardial membranes in which the embryonic heart is suspended. In the 



dorsal mesoderm 



diate mesodenn 

 lateral mcsade 



ighl and left 

 coelom confluent 



Fig. 267.- — Schematic diagrams of cross sections at various stages to show the 

 establishment of the coelom and mesenteries. (From Patten's "Embryology of the 

 Chick.") 



abdominal part of the coelom the splanchnic layers of mesoderm unite 

 above and below the aUmentary canal to form dorsal and ventral mesen- 

 teries. The dorsal mesentery persists throughout life, but the greater 



