642 
ME. W. K. PAEKEE ON THE STETJCTUEE AND 
and help to give complexity to the infoldings of the Schneiderian membrane. The 
variously roofed nasal domes are like enough to those of a Skate or Shark below, and 
their valvular cartilages are homologous ; but their roof is imperfect and, as becomes an 
air-breather, perforate (figs. 1, 3, 5, e.n.). Besides the investing bones to be described 
anon, there are three pairs of labial valvular cartilages above. The most notable pair 
look like leathern bottles, the neck of each looking inwards and forwards ; but they are 
mere “ slings ” that have lost their “ tentacular ” cord (Plate 57. figs. 2 & 3, u.l.). Below 
(fig. 6) we see this, their lower edge being inturned only slightly. The inner end of 
these conchoidal cartilages is covered with a small spatulate separate piece (fig. 5, ul. a ), 
and as this is attached at right angles to the large labial a space is formed ; this is the 
fore margin of the external nostril (e.n.). Its hind margin is formed of membrane, a large 
space existing where the aliseptals are so deficient ; across the middle of this space, another 
labial, oblong, and twice the size of the last, runs inwards and forwards to the septum 
(fig. 5, u.l. b ). Below (fig. 6, u.l. c ) another pair of spatulate cartilages (“ % prorhinals ”) are 
seen, near the septum, and having their “ handles ” looking backwards. Helping to close 
the open nasal space below (fig. 6, u.l. d ) the last pair of “upper labials ” is seen. Each 
cartilage lies inside the arcuate rim, nearly touching the prepalatine by its outer end ; 
it is a thick, short, arcuate, twisted bar of cartilage ; this bar has its exact counterpart 
in the Shark. 
Passing to the mandible and its outgrowths, we find characters very unlike those seen 
in the ordinary Batrachia. The pier of the mandible could be well traced in the last 
stage, with its flat pedicle and the elbowed rudiment of the otic process (Plate 58. fig. 3). 
The upper part of the pier is largely cartilaginous even now, but it is much hidden by 
a number of bony plates ; whilst the quadrate region is converted into a true (ichtJiyic) 
quadrate bone (Plate 59. figs. 3, 4, 8, 9, q.). The metapterygoid region may be seen as a 
tract of cartilage in the front face of the pier of the mandible, where the long processes 
of the pterygoid and squamosal, and the shorter plate of the quadrato-jugal, have been 
cut away (Plate 59. fig. 9, ot.p.,pd., pro., sq., q.j.,q.,pg.). 
There is no metapterygoid bone covering the pedicle, but merely, as in Bufo vulgaris, 
a process of the pterygoid bone (pg.). Looking at the skull from behind (Plate 59. fig. 4), 
we see that there is a large synchondrosia.1 tract connecting the prootico-exoccipital mass 
above and the quadrate below (pro., e.o., q.) ; this is the common territory of the 
tegmen tympani and “ otic process ” of the mandibular pier. This tract is also seen in 
the upper view (fig. 1), but there we only see the cartilaginous selvage which belongs to 
the “ tegmen ; ” the squamosal (sq.) covers the otic process. The backward extension 
of the quadrate angle and condyle is not equal to what is seen in the Frog and Toad 
(Plate 54. figs. 3 & 4) ; and we have here what is not seen in the common types, namely, 
a well-ossified quadrate region, as in the Osseous Fish (“ Salmon’s Skull,” plate vi. 
figs. 1, 2, q.), and to a less degree in the “ Urodela ” (Huxley, “ On Menobranchus ,” op. 
cit. plate xxx. fig. 1, Qu.). Here it is an obliquely oblong bone, oddly bent backwards 
from its metapterygoid cartilage above, and then having its base turned forwards again 
