181 



1495. The skull of a Helmet Hornhill (B*crro$ galfatwi), vertically and longitudi- 

 nally bisected. 



It show* the denser texture of the cancellous bases of the upper beak, and especially of it* 

 large upper process. The prosencephalic median septum is very dense : the septum dividing 

 the proscnceptialic from the mewucrphalic rluunber ii unusually developed. The occiput 

 has been cut away. The long postfrontal nearly touches the tquamotal. The niMtniil. 

 though smaller, is well developed. 



1496. The upper mandible, with its homy sheath, and the anterior part of the cra- 

 nium of a Helmet Hornhill (linn-nut galeatiu), longitudinally and vertically 

 bisected ; showing the thick and dense horny covering in front of the super- 

 imposed process of the mandible. Hunteria*. 



1497. The horny sheath of the upper mandible of a Helmet Hornbill (Buccrot yaie- 

 afiu). Printed by Sir Jotepk Bank, Bart., P.R.S. 



1498. A longitudinal section of the horny covering of the upper mandible of a 

 Helmet Hombill (Bucero* yaleatiut). llmtieria*. 



1499. The skull, with the horny sheaths of the mandibles, of the Bifronted Horn- 

 bill (Bucrros bicomif). lluntmait. 



1500. The skull, with the horny sheaths of the mandibles and the dried skin of the 

 head, of a Bifronted Hombill (Bucero* bicornit). .!/*. Brit. 



1501. The cranium of a Bifronted Hombill (Bucrros bicornu). The crest has been 

 removed to show the light reticulate structure of the osseous platform attaching 

 it to the upper mandible. Prrxmfrtf by Sir William Hliznrd, F.H.X. 



1502. The skull of a Bifronted Hornbill (fiucfro* bicornif), longitudinally and ver- 

 tically bisected, with part of the crest and the horny sheatlis of the mandibhv 

 removed. 



The vertical course of the nasal patoage U exposed at the base of the mandible. The pros- 

 encephalic chamber has not the detwe vertical septum, as in the Btteerot galraltu. The (mall 



