192 PROF. W. K. PARKER ON THE STRUCTURE AND 
upper margin as wings of the posterior sphenoidal region; these are the unossified 
counterparts of the “ sphenotics” of bony fishes, the roots of the “ supraorbital bands.” 
“A ligamentous band passes from this projection to the eye-ball” (Huxley, op. cit.), 
which is very small, and is attached by this band to the anteorbital (e.pa); this band is 
a membranous “ supraorbital.” 
Halfway between the ascending process and the optic passage (a.p, 11) the “ sphen- 
ethmoid ” bone (sp.e) begins; it is an ossification of the trabecula and its orbital crest, 
and therefore answers both to the orbitosphenoid and lateral ethmoid, and also to the 
primary half of the girdle-bone of those “Anura” which have an extension of bone 
into the orbitosphenoidal region, as in Dactylethra. 
This ossification reaches in front of the ethmoidal region, and affects the hind part of 
the intertrabecula and cornu trabecule (7.t7, c. i); it meets its fellow below in the 
adult (Pl. XXXVIII.). 
We have here, in bone, the simplest rudiment of the lateral ethmoid and cribriform 
plate of Man; for the olfactory nerves (1) are seen emerging obliquely from the 
cranial cavity, and escaping beneath and to the inside of the aliethmoid (a/.e), which 
answers to the roof of the “upper turbinal” of Man. These wings are straight- 
edged, look outwards and forwards, are not ossified to their end, and carry the rudi- 
mentary nasal roof (na) or “ aliseptal” cartilages; these are ear-shaped, and cover only 
part of the nasal capsule. 
Behind and below these wings another and rather smaller pair (#7) is seen; these are 
the flat hinges for the ethmo-palatine (ichthyic “ palatine”) cartilages (e.pa); they 
also are not ossified to their end. 
In front of the sphenethmoid the endocranium forms a trifoliate structure: the outer 
“leaves” are the flattened, ear-shaped, outturned cornua trabecule (c. tr); and the 
median part, which is thick and oval in the middle, ends in a rounded and papilliform 
‘* prenasal ” projection (é.¢7, py.) ; this median process is seldom seen in the Urodeles, but 
occurs in Salamandra. 
All the three terminal processes are decurved; both the upper and lower jaws are 
bent downwards, according to the primordial endocranial pattern. 
ce. The Visceral Arches of Siren lacertina. 
Attached to the hinder and lower ethmoidal wings are a pair of pyriform cartilages 
less than the nasal roofs, and attached by their broad ends; these are the ethmo- 
palatines or ¢rwe palatine elements (e.pa). These are separated by the whole orbital 
region from the piers of the mandibular arch (sp), which are very large cartilages, but 
have no guasi-symplectic outgrowth (pterygoid cartilage). 
These latter, large, multilobate cartilages are complicated by the fusion with those of 
the pier of the hyoid arch (e.hy) ; they are totally unossified (unique in this respect), and 
retain the embryonic direction, which is forwards and outwards. The dorsal end of each 
