248 
ORIGINAL ARTICLES. 
protecting the brain, it takes the place in part also of the basi- 
sphenoid, which is as little developed in Batraehia as in Eish. 
Although in many Batraehia, as for example in Salamandrina 
attenuata which I have described,* teeth are subsequently developed 
on the lower surface of the bony plate, which I regard as the body of 
the pre-sphenoid, yet this circumstance does not support Beichert’s 
view that that plate is developed from the mucous layer of the germ, 
since other bones of the head, which certainly are not developed from 
the mucous layer, e.g. the upper and under jaws, possess teeth in 
most vertebrata. 
When the osseous plate in question has begun to ossify, the sub¬ 
stance, which fills the gap between the trabeculae cranii, becomes con¬ 
verted into a very thin layer of cartilage, the edges of which pass with¬ 
out interruption into the much earlier chondrified surrounding parts 
(the trabeculae or the investing mass of the notochord generally), and 
which is to be recognized even in adult Erogs. Besides this, against 
the rule which holds good for animals higher than the Batraehia, the 
cartilage grows from the outer edges of the trabeculae into the origi¬ 
nally membranous lateral walls of the cranium, so that, at the end of 
larval life, the part of those lateral walls which lies in front of the 
auditory capsules, together with the basis cranii, forms a deep cartila¬ 
ginous groove, whilst in other animals, where the corresponding part 
of the lateral walls chondrifies, the chondrification goes on quite 
independently of the trabeculae. 
Whilst the olfactory organs increase in size, the coalesced, or an¬ 
terior part of the two cranial trabeculae gradually elongates, increas¬ 
ing in height at the same time, so that it forms a moderately high 
septum between these two organs; and it sends out on each side, not 
merely, as in the higher vertebrata, from its upper edge, but also from 
the lower, a longitudinal ridge which gradually becomes converted 
into a horizontal, moderately broad plate. Both plates, or lateral 
alsB, then partly embrace the olfactory organ of the same side, and 
are applied closely to it. Upon the upper plate a nasal bone is 
developed, while to the lower a palate bone becomes applied. The 
two cornua into which the cartilaginous nasal septum is produced 
anteriorly, bend, in the last half of larval life, outwards and back¬ 
wards round the anterior edge of the olfactory sacs, become thicker, 
but at the same time narrower and pointed, and remain permanently 
cartilaginous, like the parts from which they proceed. Between the 
two cornua the premaxillae are formed in the normal way. A vomer 
is never developed; on the other hand, at the end of the larval con¬ 
dition, or soon afterwards, ossification commences in each lateral 
wall of the most anterior part of the brain case. By the gradual 
increase of this deposit a pair of little bony plates is formed, which 
at length meet above and below and coalesce so as to form that re- 
* Zoologischer Atlas von Eschsclioltz, Heft. V. 
