212 
MR. W. K. PARKER ON THE STRUCTURE AND 
a small |J-shaped annulus ( a.ty .), over which the subcutaneous stroma is becoming 
arranged radially, and towards which the pointed end of the new columella is growing. 
In Pelobates fuscus (Plate 25) such a rudiment ossifies throughout; it stops 
growth in a form soon to be described, viz.: Rhinodermci (Plate 39, fig. 5, co.), it is 
arrested at this identical stage and does not ossify; whilst in Pseudophryne, some 
kinds of Plivyniscus, and in Bombincitor igneus it never appears ; in these kinds we 
have the counterpart of the newly metamorphosed Common Toad and Frog, and of 
many of the adult “ Urodeles,’’ 
The mandible in this stage (Plate 38, fig. 4) is formed, the mento-Meckelian (■ m.mk .) 
is forming, and the whole bar is very similar to what it will be in the adult. 
The investing bones are already well developed, but they are very thin shells at 
present, and do not cover the endocranium nearly as much as they will do; I shall 
refer, again, to these structures in describing the skull of cognate, but pigmy, or 
arrested Toads, of the Families “ Bhinodermatidse,” “ Phryniscidag,” £ ‘ Engystomidse,” 
and “ Braclrycephalidae.” 
60. Bufo vulgaris. —Adult. England. 
In describing the Bufonine skull I shall have to refer again and again to my pub¬ 
lished description both of that of the adult and larva (see Phil. Trans., 1876, Plates 54 
and 55, pp. 605-625)."" 
The skull of the adult Common Toad is short and wide, the length is only five- 
sixths of the breadth. 
In the degree of its ossification, and in the possession of three fontanelles, it agrees 
with the Common Frog ; but it is shorter and altogether a coarser and stronger skull ; 
and there are no teeth, either on the vomers or the jaw-bones. By referring to my 
published figures the reader will see that, besides these general differences, there are 
several very important morphological modifications in the skull of this species ; these 
are as follows :— 
1. The nasal roof is a narrow, jagged cartilage, confluent with the fore end of the 
septum, in front, and with the ethmoidal wings behind, but separated by a large 
“ olfactory fenestra” from the main part of the septum. 
2. The palatine cartilage is a T-shaped, distinct piece, segmented from the ethmoidal 
wing, above, and from the pterygoid cartilage, behind. 
3. The pterygoid bone ties down the pedicle, which has not lost its dorsal portion, 
and thus has never become free. 
4. The pro-rhinals are very small and turned inwards. 
5. The “annulus ” has a short posterior horn, which does not unite with the anterior 
horn. 
* In the figures the outer labial is lettered u.V-. instead of u.P .; and the deficient nasal roof is lettered 
u. Z 2 . instead of n.r. ; the description of these parts is erroneous, as I have discovered since, for I failed then 
to find the first upper labial, and mistook the nasal roof for the second. 
