DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
3U 
The outworks of this chondrocranium are being converted into bone at various 
points; the quadrato-jugal (<].J.) has grafted itself on to the quadrate (distal part of 
suspensorium), the long falcate palatine (pa.) is grafting itself on to the ethmo-palatine 
bar, and the pterygoid (pg.) —a long sigmoid bone with an internal snag—is doing the 
same to the “ pterygo-quadrate” region. 
In the Batrachia generally, the pedicle ( pd .) is also more or less ossified by the 
proper osteo-pterygoid; but here, as in Rana temporaria and R. pipiens —that old fish¬ 
bone —the “metapterygoid” ( mt.pg .) breaks out again; the possession of this centre 
is, perhaps, the only blot in the escutcheon of our native species,—in all other things 
the Batrachia may be said to “ set their clocks ” by that of Rana temporaria. 
The mandible (fig. 3) has all its parts perfect or typical. 
The columella is much more developed than, but is extremely similar to, the last; 
it has the distinct distal segmentation (Plate 5, fig. 5), but the distal piece is now 
contracted, like a “ spatula,” and has sent from its inner face a supra-stapedial band of 
cartilage upwards to coalesce with the under surface of the tegmen tympani (e.st., s.st.). 
Also the large solid mass of cartilage at the stapedial end of the bony medio- 
stapedial ( m.st .) has become a separate “inter-stapedial” (i.st), articulating with the 
stapes (st.). 
The “annulus” (fig. 1, a.ty.) is a perfect ring of cartilage as in other North American 
kinds, and as in many of those from the Oriental region. 
The “hyo-branchial” apparatus (fig. 4) is now quite normal; all the parts are fused 
together, are quite chondrifieri; and the “ thyro-hyals ” are now (typically) ossified ; 
the hyoid bar ( st.h .) is distinct from the ear-capsule. 
The nasals and premaxillaries, and their contiguous labials (n.,px., u.V-.uR.) are quite 
normal, so also are the maxillaries («.); but I can find no “septo-maxillaries”—small, 
variable, and inconstant bones; the quadrato-jugals (q.j.), as I have just mentioned, 
have united with the quadrate cartilage; and the squamosals (fig. 1) are truly elegant 
Batrachian bones, with a twisted sub-falcate upper, and a flat sigmoid lower, part. 
The “vomers” (Plate 5, fig. 2, v.) have their characteristic spikes, fore, middle, and 
hinder; the two latter enclosing the inner nostril (e.n., by mistake) largely; and a 
postero-internal, thick, dentigerous lobe. 
The parasphenoid (fig. 2 , pa.s'., pa.s.) like that of Rana pipiens (Plates 3 and 8) 
shows the very rare condition of a distinct bony centre for the point of this little dagger. 
These are the conditions of the growing skulls in this genus ; afterwards I shall show 
that many of the dwarfed and more or less generalised types are arrested, in some 
things, at certain stages that correspond with growing stages of the typical kinds. 
