7G ESSAY t>N THE DESCRIPTIVE ANATOMY OF THE 
superior surface is flattened, and comes in contact with the 
right phrenic crus and psoas muscles. Its inferior surface is 
more convex, and related to the duodenum and transverse colon. 
Its outer border is convex and smooth, and in contact with the 
liver anteriorly. Its inner border is concave and notched, con¬ 
stituting the lobes of the organ, where its vessels and ducts 
enter and issue. It is here related to the supra renal capsule, 
and more especially to the vena cava. 
The left kidney is situated further back in the lumbar region 
than the right, being attached to it, as well as to the colon and 
spleen, by peritoneum. 
Its shape is strictly that of an irregularly bent ovoid, being 
longer than the right but not so broad. Its superior sur¬ 
face is flattened, and comes in contact with the left crus of the 
diaphragm and psoas muscles. Its inferior surface is convex, 
and in contact with the transverse and single portions of the 
colon. The outer convex margin of the left kidney is oblong, 
and anteriorly related to the spleen. Its inner border is concave 
and notched, like the right, being in contact with the left supra¬ 
renal body and aorta. 
Though differing in these marked general characters the kid¬ 
neys resemble each other in several equally obvious points of 
their general anatomy. Both kidneys have a peritoneal and 
an albugineous coat, both have an excretory duct, vessels and 
nerves, with a structure also equal in the two, constituting the 
bulk of the organ. Externally to the peritoneal tunic is a more 
or less thick stratum of fat, which is more abundant in old than 
in young animals, when in a state of obesity. 
The peritoneal covering of the kidneys is incomplete, espe¬ 
cially that of the right one, whose inferior surface and convex 
border are the only parts coated by it. The left kidney is 
also covered on its superior surface to a considerable extent, 
sometimes more and sometimes less. The attachments which 
each organ contracts through the medium of this serous invest¬ 
ment have already been described. 
The albugineous tunic is fibrous, and partly sub-serous. It 
forms a distinct capsule attached to the substance of the organ 
by fibrous prolongations, which are in some parts arranged in 
pits and depressions, so as to mark out divisions on the surface 
of the kidney. In addition to this, the albugineous coat sur¬ 
rounds the vessels and ureter at the hilus, and enters the sub¬ 
stance of the organ. 
On cutting the kidney horizontally from the convex to the 
concave border, there are three different parts brought into view, 
to be taken into consideration. Firstly, a dark contour of about 
half an inch or more in thickness, being generally less at the 
