1895.] LORIUS FLAVOPALLIATUS AIS'D PSITTACUS EEITHAC0S. 381 



the same transverse line, while the two external ones probably 

 answer to the lateral ends of the M-like ridge of L. flavopalliatus 

 because a vagal foramen opens just above each of them. 



In this species there is on either side of the cranium a roughly 

 quadrilateral space bounded anteriorly by the outer end of the 

 posterior transverse basi-temporal ridge, internally by the lateral 

 margin of the foramen magnum, externally by the paroccipital 

 process, and posteriorly by a rounded prominence (exoccipital 

 prominence) running from the summit of the side margin of the 

 foramen magnum to the posterior surface of the paroccipital 

 process. In P. erithacus the conditions are similar save that the 

 exoccipital prominence is somewhat less pronounced and ridge-like. 

 In both species a foramen opens on the exoccipital prominence 

 about midway between the margin of the foramen magnum and 

 the base of this paroccipital prominence, but this foramen is larger 

 and very much more conspicuous in L. JlavoiJciUiatus. 



The side of the paroccipital process bounding this quadrilateral 

 space (the inner aspect of the process) has in both species a 

 conspicuous foramen opening into it. 



The infero-external aspect of this process is very different in 

 the two species. In L. flavopaUiatus it is wide, strongly concave 

 transversely, and looks mainly downwards. In P. erithacus it is 

 but slightly concave transversely and looks more outwards. 



The posterior end of the paroccipital process in L. Jlavopalliatus 

 is bent more sharply backwards than in P. erithacus and also some- 

 what inwards (see figs. 1 & 2 and 9 & 10). 



The basi-temporal shield is limited laterally by two very sharply 

 raised ridges, which meet together just below the eustachian aper- 

 ture and end in a median sharp-pointed process projecting forwards 

 beyond and beneath it (fig. 6, me). Between its lateral and post- 

 axial ridges the shield is smooth and slightly concave, without 

 ridges or- foramina. 



In P. erithacus its lateral ridges are much less well-defined and 

 are represented by two slightly elevated prominences each of 

 which is marked by a very narrow longitudinal groove, but the 

 shield also ends medianly in front in a pointed eustachian process 

 (me) projecting forwards beneath the eustachian opening. The 

 surface of the sliield is slightly undulating, and a little behind the 

 eustachian process is a depression behind which there may be a 

 median ridge. 



In L. flavopaUiatus there is outside each lateral basi-temporal 

 ridge a wide transverse concave surface which becomes continuous 

 posteriorly with the ventral surface of the paroccipital process. 

 It is bounded superiorly and externally by a slight ridge running 

 forwards and inwards from just below the foramen ovale and 

 ending in a small preaxiad process — the lateral eustachian process 

 (fig. 6, le). In P. erithacus this concave surface is narrower and 

 does not approach so nearly the foramen ovale, while the ridge 

 bounding it superiorly and externally ends in a more marked lateral 

 eustachian process (fig. 7, le). 



