DEVELOPMENT OE THE SKULL IN THE BATRACH1A. 
87 
be taken as typical diagrams of those parts in the “ Anura” generally ; for although 
coalesced, they show the outlines of all the parts that go to make up the whole (tigs. 1, 2). 
The tegmen cranii in the ethmoidal region is continuous with the top ol the large 
high intertrabecular crest, the outline of which is clearly seen, both above and below, 
as a gradually narrowing tract of cartilage, convex above and below, and ending in a 
free, blunt spike. Here we have the perpendicular ethmoid passing into the septum 
nasi and ending in the prenasal rostrum ( p.n .). 
In front of the etlnno-palatine bars the trabeculae have a large crescentic notch on 
each side ; here the inner nostrils (i.n.) are situated, yet at this part the latter are not 
much narrower than in the interorbital region. 
In front, they spread into wings three-fourths the extent of the auditory masses, 
behind; and each wing is divided by a large rounded notch into a large hind, and a 
lesser fore, lobe. 
The hind lobe, or angle of the subnasal lamina ( s.n.l .) forms a rounded hook in 
front, which turns inwards; on the upper surface (fig. l) each plate has a transverse 
crest, which runs inwards and articulates with the out-turned, anterior horn of the 
nasal roof-cartilage (na.). The anterior lobes of the primary trabecular cornua are 
nearly as long, and one-third the width of the hind lobes ; they are a little arcuate, 
finger-shaped, and diverge at more than a right angle ; these are the pro-rhinals 
( p.rh .). We have, thus, a five-fingered end to the chondrocranium, and these five 
lobes are all developments of the pre-pituitary on-growtlis of the three basi-cranial 
cartilages that in the post-pituitary region embrace and enclose the notochord.' 1 ' 
Over the nasal sacs, the cartilaginous roof (na.) is seen to be composed of a pair of 
ear-shaped shells, lying back to back, not touching each other, but confluent with the 
edges of the septum nasi. 
Behind, they have also united with the etlnno-palatines (e.pa.), and in front with 
the transverse ridge on the outer trabecular lobe (s.n.l.). The inner margin of each is 
semi-circular, the outer is sinuous, widest in the middle, and each end is developed into 
a cornu ; the front horn is blunt and the hinder horn sharp. On the front horn there 
is seen the second upper labial (u. I 2 .) (the first has been left unfigured with the pre¬ 
maxillary) ; between this and the front horn is the outer nostril (e.n.). 
* Yet the true slceletal axis ended behind the pitnitary space and body, and the organic fore end of the 
nenral axis ended just in front of that part, through the overbending of the vesicles of the brain. The 
continuous, or distinct, conjugating bar by which the fore-growth of the mandibular pier becomes attached 
to the ethmoid, bears an endoskeletal relation to the outer bones in the malar region. 
The angle of the “ subnasal lamina ” bears the same relation to the maxillary region , and the pro-rhinals 
to the inter-maxillary region, and these gore-oral endoskeletal and exoskeletal structures, combined, make 
up one antagonistic upper jaw, to work against the 'post-oral lower jaw. 
Moreover, there are, besides these three pre-oral rudiments (or imitative arch-piers), the “post-palatine” 
cartilage of the Axolotl, the “transpalatine” of Singing Birds, and the “ epiterygoid” of Urodeles, 
Chelonians, and Lizards, to be accounted for. These three latter, I suspect, are different modes of the 
same element. 
