218 



OSTEOLOGY OF AN SERES 



Anteriorly tbe ethmoid lias an elongo cordate outline, the base of the 

 figure abutting against the under side of the crauio-facial region. 



Viewing this skull from beneath we notice a long, narrow cleft in 

 front of the maxillo palatines and bounded on either side by a dentary 

 process of the premaxillary. This cleft is deepest behind and gradually 

 becomes shallower as it proceeds to the front, where it disappears just 

 behind the rounded mandibular apex. 



The maa Mo-palatines are thin, horizontal plates that are in contact for 

 their anterior halves in the median line, but diverge as rounded, dis- 

 tinct processes for their posterior moieties. These processes project 

 into the wide interpalatine cleft, but do not come in contact either with 

 the palatine bones nor with the vomt r. This latter is a long, thin plate 

 of bone that is grasped by the small ascending processes of the pala- 

 tines behind to anchylos with them, while above it is finished off with a 

 rib-like margin which is produced beyond the plate iu front as a long 

 spiculiform process, with its apex resting upon the middle of the max- 

 illo-palatine median suture. 



Each palatine body is a narrow lamina of bone, the anterior end of it 

 dilating somewhat before being inserted between and fused with the 

 other elements in front. 



These palatines only meet each other, and that only in a point, be- 

 hind their common seizure of the hinder end of the vomer. Nor do they 

 come in contact with the under border of the rostrum, as they are pre- 

 vented from doing that by the sessile, though large and elliptical, basi- 

 pterygoid facets found upon the latter. 



Their heads are separated behind by cpiite an interval, and each one 

 makes a peculiar combination joint with the corresponding head of the 

 pterygoid, which develops the reverse articulation for it. 



Immediately posterior to this a pterygoid supports also a sessile ellip- 

 tical facet of precisely the same character as the one referred to above 

 as occurring on the rostrum, the two coming in contact to form a per- 

 fect sliding joint, with smooth and plane surfaces opposed to each other. 



•■ • vitswed from iibnve. rnamliblere red; life size. By tbe author, from 



< ollection. 



Posterior to this articulation a pterygoid is somewhat compressed 

 from above downward, and curves gracefully outward to cover with 

 its cup like hinder end the spheroidal facet offered to it on the part of 

 the corresponding quadrate. 



