UEVELOi'iMEi^T OF THE SKULL IN THE BATRACHJA. 87 



be taken as typical diagrams of those parts in the " Anura" generally ; tor although 

 coalesced, they show the outlines of all the parts that go to make up the whole (hgs. 1, 2). 



The tegnieu cranii in the ethmoidal region is continuous with the top of the large 

 high intertrabecular crest, the outline of which is clearly seen, both above and below, 

 as a gi-adually narrowing tract of cartilage, convex above and below, and endmg in a 

 free, bjunt spike. Here we have the perpendicular ethmoid passing into the septum 

 nasi and ending in the ^^renasal rostrum [p.n.). 



In front of the ethmo-palatine bars the trabecular 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 auditoiy 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. 1) 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-growths of the three hasi-cranial 

 cartilages that in the post-pituitary region embrace and enclose the notochord.'"' 



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 ethmo-palatines (e.pa.), and in front with 

 the transverse ridge on the outer trabecular lobe (s.n.l.). The inner margin of each is 

 serai-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 (»./-.) (the Jirst has been left unfigured with the pre- 

 maxiUary) ; between this and the front horn is the outer nostril (e.n.). 



* Yet the true sl-eletal axis ended bcliind the pituitary space and body, and the onjanir fore end of the 

 neural axis ended just in front of tliat part, throuj^li the ovcrbcnding of the vesicles of the brain. The 

 amtimwiis, or didinct, conjugating bar by which the fore-growth of the mandibular pier becomes attached 

 to the ethmoid, bears an cndoskeletal relation to the outer bones in the malar reijion. 



The angle of the " subnasal lamina " beai-s the same relation to the maxillary reyioit, and the pro-rhijiala 

 to the inter-maxillary region, and these pre-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-jyicrs), the "post-palatine" 

 cartilage of the Axolotl, the " transpalatino " of Singing Birds, and the " epitcrygoid " of Urodcles, 

 Chelonians, and Lizards, to be accounted for. These thi-ee latter, I suspect, arc diffei-ent modes of the 

 same clement. 



