414 STRUCTURE AND CLASSIFICATION OF BIRDS 



On the ninth vertebra there is on the dorsal surface a fibrous 

 loop (' Donitz's bridge'), which is fibrous only in P. anliinga. 

 ossified in the three other species. Through this loop passes the 

 tendon of the longus colli posterior muscle to be inserted on to 

 vertebrae 2, 3, 4. The longus colli anterior is a very powerful 

 muscle, which ends in a long tendon attached anteriorly to the 



FIG. 193. STOMACH OF LEVAILLANT'S DARTEFX (AFTER GARROD). 



haemapophysis of cervical vertebras 8-10. A separate portion of 

 the muscle is similarly attached to the eleventh. 



The pulling back of the head preparatory to striking is effected 

 by the longus colli posterior, while the bayonetting movement 

 is produced by the longus colli anterior. 



The second characteristic feature in the organisation of Plotus 

 concerns the stomach. Though originally described by MACGILLI- 



