872 SHULL 
unpaired Presphenoid, forming with it the rostrum of the basis 
cranit; (3) the Vomer, paired or unpaired, resting upon the septum. 
V. Bones derived from, or developed upon, visceral arches, form- 
ing the appendicular apparatus of the Skull—(1) the unpaired 
ANALYTICAL DIAGRAM OF A Birp’s SKULL. 
Premaxilla ; (2) the right and left Maxille; (3, 4, 5) the right 
and left ‘“ Palatines,” Pterygoids and Quadrates—these being, as well 
as (6, 7) the right and left Jugals and Quadrato-jugals, modifica- 
tions of the dorsal half of the first visceral arch; (8) the bones 
forming the right and left Mandibule (or the lower jaw)—namely, 
the Dentals, Splenials, Supra-angulars, Angulars and Articulars—all 
these last being modifications of the ventral half of the same (first) 
visceral arch; (9) the ossicles of the ear, columella auris (p. 179), 
ANALYTICAL DIAGRAM OF THE ViscmraL ArcuEs. The dotted portions are not developed. 
being the remnants of the dorsal half of the second visceral arch 
(=the Ist branchial arch), while the remnant of its ventral half 
is transformed into the os entoglossum (p. 453); (10) the rest of the 
Hyoip apparatus formed by the third visceral (= 2nd_ branchial) 
arch, 
