386 DE. ST. GEORGE MIVART ON THE SKELETON OF [May 7, 



an angle of about 23^ in P. erithacus, and at a slightly more open 

 angle in L. fiavopaUiatus. 



In P. erithacm the lambdoidal ridge traverses the posterior sur- 

 face of the skull a little below its dorso-ventral middle. Above this 

 the occiput is rounded. 



This lambdoidal ridge is met (as before noted) by the posterior 

 continuation of the ridge which bounds the temporal fossa infe- 

 riorly, and at the point of junction develops an obscurely marked 

 prominence we have called the squamosal prominence (see fig. 2, 

 psp). Thence a slightly marked ridge descends vertically to 

 another small prominence or exoccipital process. From this latter 

 another very slightly marked ridge — the occipital ridge — passes 

 inwards and upwards till it nearly joins the lambdoidal ridge, and 

 thus a triangular surface becomes defined. Then this shght occipital 

 ridge continues on inwards and downwards till it meets a promi- 

 nence running upwards from the middle of the dorsal margin of the 

 foramen magnum to the lambdoidal ridge, or may descend to the 

 margin of that foramen, and thus a second triangular surface 

 becomes defined. Beneath the occipital ridge there is, on each 

 side of the median occipital protuberance, a rather extensive but 

 shallow concavity. 



In L. JlavopalUatus the lambdoidal and occipital ridges are both 

 about equally, and only very slightly, prominent and so close 

 together that only a faint and narrow groove runs between them. 

 The squamosal prominence is very slight, and the exoccipital pro- 

 cess hardly to be detected. The median rounded occipital promi- 

 nence is much more marked, and so is the concavity on either side 

 of it, but the degree of concavity is more uniform over this concave 

 space than in P. erithacus and is most marked just below the 

 occipital ridge. 



In P. erithacus each paroccipital process is somewhat pyramidal, 

 but may be said to present two siu-faces limited by a ridge which 

 extends backwards from the hind end of the ridge bounding 

 laterally tlie basi-temporal shield to the apex of the process, and 

 thence upwards and slightly outwards, finally curving inwards to 

 the exoccipital process. 



The outer surface of the paroccipital process is slightly convex 

 transversely and very slightly concave in the opposite direction. 

 The inner surface is very strongly convex transversely and medianly 

 concave dorso-ventrally. The process is bent much backwards 

 (but hardly inwards) towards its apex. 



In L.fiavopalliatus it presents more exclusively two surfaces, the 

 ridge which diAides them from each other being sharper. It is so 

 bent that what corresponds to the outer surface of the process in 

 the other species here looks mainly downwards. It is also con- 

 cave both transversely and antero-posteriorly. The opposite 

 surface looks mainly upwards and is strongly convex transversely 

 at the root of the process, but concave in the opposite direction, 

 especially towards its apex. 



The process is bent rather more inwards than in P. erithacus, 

 and ver}' much more strongly and sharply backwards. 



