THE MUSCULATURE OF THE TRUNK. 307 



produced this drawing for us in his Key to North 

 Aynerican Birds, the second edition (p. 206). 



According to Sir Eichard Owen, " The diaj^hragm 

 presents more of its mammalian character in the Apteryx 

 than in any other known bird. It is perforated by 

 vessels only, in consequence of the non-development 

 of the abdominal air-cells. The origin corresponding 

 to that of the lesser muscles in Mammals is by two 

 strong and distinct, short tendinous pillars from the 

 sides of the body of the last costal vertebra ; they are 

 united by a strong tendon or fascia, forming the anterior 

 boundary of the aortic passage. The tendinous pillars 

 may be traced forward for some way in the central 

 aponeurosis, expanding without crossing ; they are 

 then lost in that aponeurosis, which is perforated by 

 the gastric arteries and veins, divides anteriorly to 

 give passage to the gullet and the apex of the heart, 

 expands over the anterior part of the thoracic air-cells, 

 and becomes, at its lateral circumference, the point of 

 attachment of muscular fil^res arising from the inner 

 surface of the anterior ribs, and forming apparently 

 a continuation of the transver sails abdominis " {A7iat. 

 of Verts., vol. ii. pp. 91, 92). 



Up to the present time I have made no exhaustive 

 examinations of the dia/phragwi in other birds, as I hope 

 to on future occasions. For a number of reasons I 

 look forward to a study of its form in the Vultures 

 and Herons with no little interest. 



149. The levator coccygis^ I believe to be the 

 detached caudal extremity of the longissimus dorsi 



^ Seven muscles, as a rule, seem to control the movements of the 

 tail in most birds, I believe in all ordinary birds. These, as I have 

 already said in the text, I have attempted to give names, or choose 

 names for them from those they have already received at the hands 



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