1895.] LOBIUS FLAVOPALLIATUS AND PSITTAOTJS BBITHACTTS. 365 



and the palatines also diverge slightly more ventrad. The man- 

 dible has its antero-dorsal margin more angular instead of rounded, 

 resembling a very obtuse pointed arch inverted (see figs. 18 & 19, 

 p. 393). 



It differs also in not having lateral defects of ossification and in 

 the less relatively vertical extent of the most postaxial part of each 

 ramus. 



The GEifEEAL posTEEioB ASPECT of the skull (see fig. 11, p. 385) 

 presents us with a dorsal margin more flattened than in P. enthacus. 

 Its surface is less concave medianly and less convex on either side of 

 such concavity. The palatines diverge slightly more ventrad, and 

 between them the bony beak shows a sudden narrowing between 

 the lateral tooth or notch of either side, and ventrad of this it is 

 narrower and more pointed. The quadrates jut out sUghtly less 

 instead of decidedly more than the postorbital processes, and the 

 middle of the occiput, just above the relatively somewhat wider 

 foramen magnum, presents a rounded more marked convexity from 

 side to side. 



The apex of the mandible seems more prolonged, showing more 

 of the ventral surface of the relatively more extensive symphysial 

 portion. 



Detailed Description. 

 I. The Bony Beak ok Prosopiusi \ 



The prosopium, when viewed laterally (see fig. 1), shows a 

 dorsal margin which descends preaxiad in front of the nares, less 

 sharply than in P. enthacus, though from just over the tooth on the 

 ventral, or tomial, margin it arches even more rapidly ; so that the 

 apex of the prosopium descends rather more vertically, while it is 

 proportionally narrower antero-posteriorly, where it begins to pro- 

 ject ventrad of the line of the tomial margin, and is more pointed 

 towards and at its apex. From a little in front of the preaxial 

 margin of the nares back to the articulation of the prosopium with 

 the cranium, the dorsum thus viewed is almost straight. 



The nares are each longer antero-posteriorly and seem narrower 

 dorso-ventrally because they look more upwards and less outwards 

 than in P. enthacus. Their preaxial margin rises as a somewhat 

 more marked ridge, while the surface of the prosopium in front of 

 and below each nostrD presents no depressed fossa. 



In P. erithacus, on the other hand, there is (see fig. 2) just in 

 front of and below each nostril a depressed area (da), the greatest 

 breadth of which is more than two-thirds the diameter of the 

 nostril, and is bounded below by a very marked groove which runs 

 postaxiad to the postaxial border of the nostril, which border may 

 be perforated by a series of small foramina, or these may be 

 replaced by notches as in L. jlavopalliatus. 



''■ By this term I intend to denote the whole ossified mass in front of the 

 cranio-facial articulation and the articulations of the zygomata and palatines. 

 It includes the premaxilla, the maxillte, maxillo-palatiue processes, the nasals, 

 and the ethmoidal and turbinal ossifications of the beafe. 



