212 MR. W. K. PARKER ON THE STRUCTURE AND 



a small (J-^'^'i^H^ed annulus {u.tij.), over which the subcutaneous stroma is becoming 

 arranged radially, and towards which the pointed end of the new columella is growing. 



In Pelohates fuscus (Plate 25) such a rudiment ossifies throughout; it stops 

 growth in a fonn soon to be described, viz.: RJiinoderma (Plate 39, fig. 5, co.), it is 

 arrested at this identical stage and does not ossify ; whilst in rseudophyijne, some 

 kinds of Phri/niscus, and in Bomhinator 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 " Ui'odeles.'' 



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 

 axTcsted Toads, of the Families " Pihinodermatidie," " Phryniscidse," " Engystomidse," 

 and " Brachycephalidse." 



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 skvdl 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 X'shaped, distinct piece, segmented from the ethmoidal 

 wing, above, and from the pterygoid cartilage, behind. 



3. The pterygoid bone ties downi the pedicle, which has not lost its dorsal portion, 

 and thus has never become free. 



4. The pro-rhinals are veiy small and turned inwards. 



5. The " annulus " has a short posterior horn, which does not unite with the anterior 

 horn. 



* lu tlie figures the outer labial is lottcrcil ti.l^. instead of u.l-. ; and the deficient nasal roof is lettered 

 ll.l-. instead of n.r. ; tlio 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. 



