376 . DE. ST. GEORGE MIT ART ON THE SKELETON OP [May 7, 



axiad. In L. fiavopalliaius it appears, for the most part, above the 

 zygoma. 



The side wall of the skull seen laterally within the circle of the 

 parts hitherto described presents the following characters : — 



The anterior portion of the inferior margin (preaxiad of the 

 junction with the palatines) does not ascend preaxiad so sharply 

 in L. JiavopalUatus as in P. erithacus, the angle formed by it with 

 the inferior margin of the basis cranii being about 155° instead of 

 140°. The inferior margin behind the junction with the palatines 

 is rather more concave, and its general trend is nearly in a straight 

 line with the line of the palatine attachment, whereas in P. erithacus 

 these two lines form an angle of about 160°. 



In both species a prominence — the septal process — is developed 

 at the anterior end of the antero-inferior margin of the cranium 

 (figs. 6, 7, 9, & 10, sp), but it is sharper and more prominent in 

 L. jiavopalliatus than in P. erithacus. In both species the side 

 wall of the skull seen within the orbit consists of an antero-inferior 

 septal part (presenting an almost vertical, slightly undulating 

 surface, bounded above and behind by the olfactory and optic 

 foramina) and a postero-superior surface. The latter inclines out- 

 wards and upwards till it reaches the superior margin of the orbit, 

 and presents a smooth surface strongly concave antero-posteriorly 

 and slightly so transversely. It is bounded inferiorly by a trans- 

 verse ridge (figs. 9 & 10, tr, pp. 383, 384), which runs from a point 

 just external to the small foramina beside the optic foramen, out- 

 wards to the postorbital process. This ridge is much more marked 

 and distinct in L. flavopalliatus than in P. erithacus. 



Near the postero-inferior angle of the septal part is a slightly- 

 marked concavity, which runs forwards from a small rather deep 

 fossa, which is bounded externally by a small process — lateral 

 eustachian process (figs. 6 & 7, le) — which extends forwards to a 

 very slight degree further than the median eustachian process (me), 

 which projects preaxiad beneath the eustachian aperture. This 

 fossa is more marked in L, JlavopalUatiis than in P. erithacus, but 

 the lateral eustachian process is less sharply prominent. 



Above this concavity, between it and the optic foramen, is a 

 marked convexity which extends forwards to a little in front of the 

 latter. This convexity is relatively, as well as absolutely, narrower 

 in L. Jiavopalliatus, and is indeed reduced to a mere rounded ridge 

 passing forwards and slightly upwards to just in front of and 

 beneath the optic foramen. In the superior portion of the septal 

 part there is a coiicavity just below^ the large olfactory opening, 

 which is much more marked in P. erithacus. In both species, in 

 front of the large apertui-e just named, a prominent ridge — the 

 crucial ridge — runs outwards and forwards from about the middle 

 of the front boundary of the olfactory aperture and bounds the 

 preorbital foramen below, ending at the inferior margin of the 

 lachrymal (figs. 9 & 10, cr), and bounds postaxially the concavity 

 last mentioned. The large olfactory aperture at the antero-dorsal 

 part of the septum is subreniform and about twice as long as broad 

 in P. erithacus. In L. Jiavopalliatus it is more rounded. 



