1895.] LOEItrS FLAVOPAILIATTJS AND PSITTAOUS EEITHACUS. 335 



what hourglass-shaped, with two slight concavities to articulate 

 with corresponding slight convexities on the pleurosteon {plu) 

 of the sternum. 



They increase rapidly in length from the first to the fifth ; they 

 are also somewhat longer, relatively, in L. Jiavopalliatus than in 

 P. erithactts, especially the first on either side. 



In P. erithacus it is shorter than the distance from the apex of 

 the first thoracic rib to the ventral margin of the uncinate process. 

 In L. flavopalliatus it is longer than that distance, and the same is 

 the case as regards the three following sternal ribs in that species. 

 In P. erithacus the three following ones about equal the length of 

 their corresponding thoracic rib, from its apex to the ventral 

 margin of the uncinate process. 



Fig. 21. 



m 



Ventral aspect of sternum of Psittacus erithacus. 



m. Manubrium. 

 p. Lateral angle. 

 pn. Pleurosteon. 



ca. Costal angle. 

 do. Defect of ossification. 

 h. Muscular impression. 



The sternal rib corresponding with the first floating thoracic 

 rib does not articulate with the sternum, but rather appUes itself 

 to the postaxial surface of the fifth sternal rib near to its distal 

 end. 



