210 
MR. W. K. PARKER OK THE STRUCTURE AND 
last; and this part shows, on its under surface, threads of new membrane-bone— 
the parasphenoid (fig. 10 , pa.s.) is appearing. 
The notches for the inner nostrils (i.n.) narrow the skull very much; and in this, 
as in the last, the quadrate cartilage (q.) shows a slight enlargement, which is 
attached by a membranous ligament to the point of the cornu ( c.tr .) in front of the 
notch; the projection on the quadrate part of the suspensorium is the rudiment of the 
pre-palatine spike. 
The rudimentary ethmoidal wing ( al.e .) is a mere angular projection at present, 
and is much smaller than in the last kind ; the elevation on this band is the rudiment 
of the post-palatine bar (pt.pa.). The mandibles ( mk .) are like those of the last, but 
not so massive; the same may be said of the lower labials (/./.). 
But the upper labials (u.l a .n.l b .) differ from those of the last Tadpole; they are 
formed as two on each side, at the first, and do not become two by segmentation. The 
two inner pairs, if melted together, as in the larva of Rana pipiens, would answer 
to the anterior dorsal cartilage of the Lamprey ; the styliform outer cartilages answer 
exactly to the external pieces in that Fish. 
Here the orbitar process ( or.p .) is still further from the ethmoid than in the last, 
and yet it possibly may unite with it afterwards. 
The hyoid bar (c.hy.) is narrower in its shaft, and dilates into two still more 
projecting angles distally; the hinder of these is the stylo-hyal rudiment, the large 
cells at the lower end form part of the basi-hyal tract. Part of the first “extra- 
branchial” ( ex.hr h) is shown in relation. In neither of these instances is there any 
rudiment as yet of an “ epi-hyal ” element. 
A comparison of these crania with those of the larval Frogs, already described, will 
show to what degree the skull may differ in its initial ( Petromyzine ) stages. I now 
come to the description of the newly metamorphosed skull of this Toad, to be used as a 
standard of comparison in describing the skulls of the small, arrested glandless Toads 
(“ Phryniscidae,” “ Engystomicke”). These small kinds will be found to have skulls 
arrested at various points that correspond with what is seen at the different periods of 
life in the higher and more developed kinds. They also show very instructive 
instances of a sort of relapse into old ichthyic conditions; they resume characters that 
have been suppressed in the more normal and better developed Anara. 
59 (continued).— (B) Skull of Bufo lentiginosus ,—Recently metamorphosed; inch long. 
In the skull of the young Toad of the first summer (Plate 39, figs. 7, 8, 9) the length 
and breadth are equal, and the quadrate condyles ( q.c .) reach, as yet, no further back 
than the Eustachian openings (eu.). Up to that part the form of the skull is a very 
neat semi-ellipse, and behind the round edges of the tegmen tympani (right and left) 
( t.ty .), the epiotic eminences ( p.s.c .), and the occipital condyles ( oc.e .), all may be said 
