6 ATRESIA OF THE AORTIC ORIFICE. 



The abrupt increase in the size of the aorta at the site of its 

 branches is of interest. 



The value of the specimen, it appears to me, lies in the fact 

 of its having a direct bearing upon the theory of the develop- 

 ment of the interauricular septum and orifice. 



In looking over the literature, I am unable to find any 

 similar anomaly. 



There have been several instances of atresia of the pulmonary 

 artery reported, most of which were associated with errors in 

 the development of the inter-ventricular septum.^ 



1 Julius Aru old, Firchoin's Archiv, March 1868, p. 449. T. B. Peacock, Trans. 

 Path. Soc, vol. XX. p. 61. Ibid., p. 87. 



