114 Proceedings of the Royal Physical Society. 



wall of the abdominal cavity, being retained in position by 

 the peritoneum, which covered the visceral or ventral aspect 

 of each kidney, and was reflected opposite the mesial interval 

 between the two kidneys in the form of a mesial longitudinal 

 sling — the mesentery — supporting the intestine. The anterior 

 end of the right kidney was opposite the hinder margin of 

 the transverse process of the 2nd lumbar vertebra (lumbo- 

 caudal), while its hinder end corresponded to the anterior 

 border of the transverse process of the 9th lumbo- caudal 

 vertebra. Its extreme length measured 13 cm., its width 

 6*3 cm., and its greatest thickness (dorso -ventral) was 3'8 cm. 

 The anterior end of the left kidney was opposite the trans- 

 verse process of the 3rd lumbo-caudal vertebra, while its 

 hinder end corresponded to the transverse process of the 9th 

 lumbo-caudal vertebra. In length it measured 12 "6 cm., 

 in width 7*1 cm., and in thickness 3*4 cm. There was thus 

 comparatively little difference between the proportions of 

 the two organs, and it was the left one which was placed 

 slightly nearer to the tail. Neither kidney presented any 

 resemblance to the bean-shape which is so usually regarded 

 as a characteristic feature of the organ. It is worthy of note 

 that Daudt ^ notes the bean-shaped appearance of the kidneys 

 in one of his smallest embryos, but in the adult organs we 

 have not found this feature, nor any very marked difference 

 between the two organs. Each kidney presented three 

 definite surfaces, viz., dorsal, mesial, and ventral, separated 

 from each other by three distinct rounded borders, viz., 

 dorso-mesial, ventro-mesial, and external or lateral (PI. II. 

 Fig. 3). 



The dorsal surface of each was smooth generally, and 

 slightly concave for adaptation to the mass of lumbar pre- 

 vertebral muscle, but the front part of this surface was in 

 contact with the diaphragm. Grooves of different sizes upon 

 this surface indicated contact relationship with parietal 

 blood-vessels. 



The mesial surface was very distinct, and corresponded to 

 the hinder three-fourths of the entire length of each kidney. 

 It was clearly delimited from the dorsal and ventral surfaces 

 ^ Daudt, loc. cit. 



