46 F. W. THYNG 



side of the oesophagus to the diaphragm. It then passes be- 

 tween the oesophagus and diaphragm and ends at a situation 

 approximately corresponding to the level of the most caudal 

 extension of the right pleural cavity. This diverticulum is 

 ventral to the main pleural cavity and evidently corresponds 

 to the space, termed by Broman ('04) the infracardial bursa. 

 The infracardial bursa in this case differs from that described 

 by Broman in that the primitive connection with the pleural 

 cavity has been retained. The retention of this connection is of 

 interest in that such a recess of the right pleural cavity exists 

 normally in animals possessing an infracardial lobe of the right 

 lung, and may be expected to occur occasionally in man. 



UROGENITAL SYSTEM 



The parts of the urogenital system are shown in plate 2 in 

 which the urogenital sinus, the left Wolffian body and duct, 

 the left metanephros and ureter, the left genital ridge, and Miil- 

 lerian duct are shown from the left side. 



Wolffian ridge and body. The Wolffian ridge extends almost 

 the entire length of the abdominal cavity, its anterior three- 

 fourths being occupied by the Wolffian body. The ridge tapers 

 off bluntly at its cephalic end ; caudad of the area of mesonephritic 

 tubules {T.W.) it dwindles to a slight elevation upon the abdom- 

 inal wall in which the Wolffian duct (D.W.) passes to the urogeni- 

 tal sinus {S.u.-g.). Under the influence of the rapidly growing 

 liver and suprarenal glands the ridge has moved laterally from 

 its primitively dorso-medial position. 



Wolffian duct. The Wolffian duct (D.W.) passes through the 

 ventro-lateral region of the Wolffian body receiving the tributary 

 mesonephric tubules (T.W.). From the caudal end of the 

 Wolffian body it extends through the remainder of the Wolffian 

 ridge to end by piercing the dorso-lateral wall of the urogenital 

 sinus (S.u.-g.). Close to its entrance into the sinus there is a 

 slight dorsal enlargement of the duct which suggests the first 

 anlage of the seminal vesicle. It should be noted, however, that, 

 according to the investigations of Pallin ('01), the vesiculus 

 seminalis first ap])ears at a much later stage of development. 



