388 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 5° 



however, besides these, constant processes more 'like the diverticula 

 of other sacs. Such are the diverticula pelvica, in the vicinity of the 

 lumbar vertebrae, and the diverticula inguinalia, surrounding the 

 head of the femur. The former almost completely surround the 

 kidneys, and extend laterally some distance beyond them. Two pair 

 of processes arising from them enter the ilium and the sacrum, 

 while others extend forward to a considerable distance. Occasion- 

 ally some of the latter reach, as slender folds, as far as the neighbor- 

 hood of the posterior border of the lungs. I have often seen a fold 

 of this kind over the proventriculus. In fig. 1 1 this diverticulum is 

 represented as not extending so far forward. 



The inguinal diverticula appear to be quite constant in the pigeon. 

 I will give a more detailed account of them because they have not 

 been described by previous authors. 



The Diverticula Inguinalia 



The inguinal diverticula surround the head of the femur and send 

 slender processes in between the muscles of the thigh. From each 

 of the two abdominal sacs a rather wide canal arises which passes 

 out from the abdominal cavity at the acute, backwardly directed 

 angle between the lateral edge of the prseacetabular portion of the 

 ilium (pars glutsea) and the musculus ilio-femoralis internus. This 

 canal extends outside the abdominal cavity forming a little sac, the 

 diverticulum femorale anterius (figs. II and 12, DFA), which over- 

 lies the musculus femori-tibialis. This diverticulum is usually con- 

 nected with the abdominal sac not only by this canal, but also by 

 another narrower tubule, the canalis prseacetabularis (figs. 11 and 

 12, CPRA), which lies in front of the other, and runs along the 

 lateral margin of the pars glutsea ilii. In one case this canal, which 

 passes over the musculus ilio-femoralis internus, gave off an acces- 

 sory dendritically ramified branch. This may have been a malfor- 

 mation. The diverticulum itself consists of several chambers freely 

 communicating with each other, and occupies the space between the 

 ilium, the musculus ilio-femoralis internus, the three united musculi 

 ilio-trochanterici anterior, posterior and medius, the flat, tendon-like 

 end of the musculus ilio-femoralis externus, and the head of the 

 femur. One of these chambers, the diverticulum femorale superius 

 (figs. 6, 11, and 12, DFS), is flattened, and extends between the 

 musculi pubo-ischio-femoralis, femoro-tibialis, ambiens, and ilio- 

 tibialis internus. Another diverticulum arising from the abdom- 

 inal sac, the diverticulum femorale posterius (figs. 11 and 12, 

 DFP), passes out through the foramen ischiadicum. This forms- 



