PLATE IX 



Plate IX is from the upper surface of a section through 

 the upper third of the body of the sixth thoracic vertebra 

 posteriorly and the upper part of the articulations of the 

 third costal cartilages with the sternum anteriorly. The 

 plane of the section is 1.8 cm. anteriorly and 2.3 cm. 

 posteriorly, below the plane of the last section. The 

 anterior margin is 1.8 cm. lower than the posterior. 



The cavity of the left auricle is divided into an anterior 

 and a posterior chamber by a peculiar thin fibrous septum, 

 perforated by several foramina, which permitted the free 

 passage of blood through the auricle. The lower portion 

 of the septum is shown in Plate X. This anomaly is fully 

 described in the Journal of Anatomy and Physiology, 

 XXXIX. p. 69. 



