52 



H. VON W. SCHULTE 



and differ in no important character here in the middle cardiac 

 plate and in the myoepicardial mantles from those observed in 

 the splanchnopleure at large. I shall recur to this field of mes- 

 enchyme and endothelium in connection with the description 

 of the endocardium. The middle plate is demarcated from the 

 mantle on each side by a sulcus which gradually becomes shal- 

 low and is effaced as it is followed caudad. 



'i 



Fig. 3 Myoei)icar(lial mantle of a cat eml)ryo of eleven pairs of mesodermic 

 somites. Columbia Collection, No. 534. X 300. Reduced one-half. 1, Mid- 

 dle, cardiac plate; 2, bulbus; .3, ventricle; 4, bulbo-ventricular sulcus; .5, atrio- 

 venous angle. 



The mantles in their ventricular segments are dorso-ventrallj' 

 flattened and of great transverse extent. Between them in 

 ventral view the middle field forms a flat depression. The bul- 

 bar segments are close together but separated by a deep cleft, 

 the roof of which is continuous with the middle plate. They 

 are much narrower and less flattened than the ventricles. 



