1895.] LOEItrS FLATOPAllIATUS AND PSITTACUS BEITHACtXS. 333 



below and more so dorsally. The superior margin of the plate is 

 in the form of a thin crest convex medianly and bifurcating 

 laterally at its postaxial end ipy), at the dorsal margin of the 

 upper flattened part of the hinder margin. 



In P. eritJiacv^ the pygostyle is essentially similar, save that it is a 

 triangular rather than a quadrate plate. It would resemble that of 

 L. jlavopalliatus if from the latter all was cut off preaxial to a line 

 passing from the superior extremity of its hinder margin obliquely 

 downwards and forwards to a point between the prezygapophyses. 



The Eibs. 



There are eight or nine dorsal and five ventral ribs on each 

 side (figs. 12 & 14). 



The Dorsal Ribs. 



In both species there are two cervical ribs and six or seven 

 true thoracic ribs, whereof five are articulating with the sternum, 

 while one or two are floating ribs. 



The Cervical Bibs. 



Thefirst cervical rib is, in both species, long, slender, styliform, 

 and devoid of any uncinate process. The tubercular and capitular 

 processes are of about equal length. 



The second cervical rib is about one-third longer than the first 

 and generally bears an uncinate process (tqy). If so this is short 

 and does not expand dorso-ventrally at its distal end. The 

 capitular process is somewhat longer than the tubercular one. 



T7ie Thoracic Ribs. 



The first thoracic rib is a little longer and stouter than the 

 second cervical, and its uncinate process (tqy) expands distally into 

 a short ventrad and longer dorsad and postaxiad process, so it is 

 much longer dorso-ventrally than antero-posteriorly. 



The second thoracic rib is again sUghtly longer, while its uncinate 

 process has a longer dorsal process and a shorter ventral margin. 

 The tuberculum is slightly more distant from the capitulum than 

 in the first true rib. 



The third thoracic rib carries a little further the same modifica- 

 tions, save that the uncinate process in L. fiavopalliatus loses 

 entirely the quadrate shape and is subtriangular with a truncated 

 apex. Its distance from the distal end of the i-ib is also greater. 

 It may still be subquadrate in form in P. erithacus. 



The fourth thoracic rib has in the last-named species a much 

 smaller and simply shaped uncinate process, which is still further 

 removed from the rib's apex. 



L. fiavopalliatus differs from P. erithacfus in that all the ribs are 

 more slender (relatively as well as absolutely), while the uncinate 



