OCR Text |
Show 1895.] LORIUS ELAVOPALLIATUS AND PSITTACUS ERITHACUS. 383 lachrymal is broader, especially at the dorsal margin of the external lachrymal groove. Its greater length causes it also to be more visible alongside of the zygoma, The paroccipital processes are much more visible than in P. erithacus, and descend, very decidedly, below the quadrates. The palatine and pterygoid angles are much as in P. erithacus. When the quadrate is removed w e find, in both species, that the glenoid fossa of the squamosal is visible at the root of the ventral surface of the sphenotic process. Within this is a narrow rough surface which separates the glenoid fossa from the smaller, more internal, fossa of the pro-otic, which serves for the articulation of the inner tubercle of the quadrate. Anterior aspect (prosopium being removed) of Psittacus erithacus. bts. Basi-temporal shield. cr. Crucial ridge. ipc. Inner precranial foramen. I. Lachrymal, forming the preorbital prominence. oc. Occipital condyle. ope. Outer precranial foramen. opf. Optic foramen. par. Paroccipital process. po. Postorbital process. sp. Septal process. sph. Sphenotic process. tg. Transverse groove. tr. Transverse ridge. On the removal of the prosopium, the anterior aspect of the cranium shows medianly, in P. erithacus (fig. 9), the prominence of the base of the cranial septum, wdtb the slightly marked septal process (sp). O n either side of this median keel are the large olfactory apertures. Dorsad is the surface of the frontal and beneath it the transverse groove (tg) for the dorsum of the prosopium, the fossa? at the outer ends of which receive its lachrymal processes. Beneath these two fossae is the swollen preaxial surface of the lachrymal (/) with its depending process transversely grooved externally. Within the lachrymal on each side, and just mesiad of the fossa for |