18/2.] LATELY LIVING IN THE SOCIETY'S COLLECTION. 



359 



Some further points in the anatomy of this bird are not without 

 interest. 



There are three parietal abdominal muscles as usual, the muscular 

 fibres of the external and internal being nearly parallel and trans- 

 verse, while those of the intermediate one are longitudinal. They 

 each send down a dense fascial attachment to the pubic bone ; and a 

 semilunar free margin between the ilium and the superior pubic 

 crest appears closely allied to Poupart's ligament, the anterior crural 

 vessels and nerves going underneath it to enter the leg. It may be 

 here mentioned that the main vein of the thigh is the internal saphe- 

 nous ; but the main artery is the one that goes through the sciatic 

 notch, therefore the sciatic. These come into relation with one 

 another in the loop for the biceps tendon at the knee. 



Exactly in the middle of the anterior border of the pubic portion 

 of the innominate bone there is a small thin plate of osseous tissue 

 which is connected with the pubis by strong fibrous bands, and 

 which is continued anteriorly and superiorly by cartilage for some dis- 

 tance, when it becomes continuous with the tendons of the parietal 

 abdominal muscles, being most connected with the external oblique. 



Portions of the external surface of the left pubis and ischium of the Ostrich. 

 The small osseous plate (a) attached to the pubis is represented partly sur- 

 rounded by cartilage. 



In dry skeletons a slight thickening of the anterior border of the 

 pubic bone indicates the attachment of this ossification in most ; but 

 in one of the three skeletons in the British Museum this bone is 

 anchylosed on one side, and Mr. Gerrard has specimens in which 

 both are still attached. A diagram of the Ostrich's pelvis in Mr. 

 Haughton's paper also shows this bone anchylosed, though no men- 

 tion is made of it in his paper. 



It would be extremely interesting to make out the homology of 

 this small but perfectly independent ossification. Its relation to the 



