DEVELOPMENT OF THE SKULL IN THE BATKACHIA. 
607 
is crested above at its outer part, whilst the inner, rounded end is enclosed in a fold of the 
premaxillary, the trihedral part lying between the arms of the curious horseshoe-shaped 
“ septo-maxillary ” (fig. 6, s.mx.). 
Possibly in old Frogs, certainly in full-grown common Toads, the second labial ( u.l. ") 
coalesces with the chondrocranium. 
The deficient roof arising from the septum nasi is here largely supplemented by the 
second upper labial ( u.l ."). This is, on the whole, lanceolate, but it is twisted in a sigmoid 
manner, and is irregularly dentate, and even fenestrate, on its outer margin. The ends 
are narrow ; the fore end has coalesced with the stunted alinasal cartilage ( al.n .), and 
the hinder end with the antorbital , or palato-trabecular bar, near its junction with the 
ethmo-palatine (p.tr., e.va.) An irregularly crescentic membranous space separates the 
inner edge of the second labial from the aliseptal fold. This valve to the outer nostril 
corresponds to the “ appendix alse nasi ” of the mammal (“ Pig’s Skull,” plate xxxvi. fig. 1, 
ap.an.) ; and the small inturned cornua trabeculae answer to the “recurrent cartilages” 
of the Bird and the Pig (same fig., rc.e.). 
I spoke of lateral cartilaginous outgrowths from the chondrocranium in front of the 
girdle-bone. These, which look also somewhat forwards, are the “ conjugational pro- 
cesses ” that run out to unite the trabeculae with the palatal bar. They are in the Toad 
(not in the Frog) instructively segmented off from the orbital process of the palatine or 
ethmo-palatine (figs. 3 -5,p.tr., e.pa.)* . 
In front of the girdle-bone, where the olfactory crura pass out, the true olfactory 
region is the recess on each side, backed by the narrow antorbital, on which no “ middle 
turbinal ” is formed ; roofed by the “ aliethmoid ” and aliseptal (from, which there grows 
no “ upper turbinal ” behind and above, nor “ lower turbinal ” in front and then below) ; 
and is floored by the outspread, concave, subnasal trabecular leaf. Laterally in the skull 
there is no true bone from the girdle in front to the great openings for the 2nd and 5th 
nerves behind. Infero-laterally, the prootic bone (pro.) creeps along the alisphenoidal 
region, half embracing the great optic passage (2). Further back each prootic seeks its 
fellow, but stops short a little within the edge of the parasphenoid ; enough, however, 
is found to enclose the trigeminal nerve (5), the foramen ovale and foramen rotundum 
being all one passage, and enclosed by the “ petrous bone ” (prootic), A line drawn 
through the cranial trough a little in front of the hinder edge of the girdle-bone, and 
another through the middle of the optic passage, would be true landmarks of the anterior 
sphenoid, which we see is soft, or partially calcified (superficial endostosis), or has a 
* This segmentation throws light upon the connexion of the palatine with the ethmo-trabecular structures in 
the Vertebrata generally. In the lower Urodela, e.g. Proteus and Menobranchus, the ethmo-palatine bar is all 
that is chondrified of the pterygo-palatine arcade (Huxley, on MenobrancJius, Proe. Zool. Soc. March 17, 1874 
p. 190, pis. xxix., xxx., A.o). In these the trabecula grows out towards this palatine rudiment, but not so much as 
in the Toad. In the Frog (figs. 1 & 2, e.pa.,p.tr.) the two bars run into each other. In the Salmon there is a joint 
(“ Salmon’s Skull,” Phil. Trans. 1873, plate vi., e.pa.), and as a rule the orbital or ascending part of the palatine 
is distinct from the trabecular outgrowth ; the ethmo-palatine, in many Birds, is developed into the very variable 
“ os uncinatum.” (See Trans. Zool. Soc. 1875, pis. liv.-lxii., for several instances of this bone in the Passerines.) 
