572 
MR. W. K. PARKER OK THE STRUCTURE AND DEVELOPMENT 
behind the feeble, facial, dentigerous parts of the premaxillaries, they run back to the 
antorbital cartilage, and are one third the length of this skull. The inner nostril ( i.n .) 
is outside their hinder part, and they there join the pterygo-palatines {p-pg-)- 
The lanceolate vomers diverge considerably behind, and are slightly out-turned ; they 
form the bony margin of the face in front, as there are neither maxillaries, nor nasals, 
nor ectoethmoids in this type. 
The next pair are of the same length as the vomers ; these bones, the pterygo-pala- 
tines (p.pg.), are more developed here than in Siren lacertina, where there is no ptery- 
goid process, the plate being arrested at the same stage as in newly hatched Axolotls ; 
in Proteus they correspond with the 4 th stage of the Axolotls (Plate 22. figs. 4, 5, p.pg.), 
in which the short dentigerous bony plate has sent a ragged process of bone backwards 
into the pterygoid region. In Proteus the bone is shaped like a “ battledoor,” but the 
handle is pointed ; a few teeth run along the middle of the broad part ; the pointed end 
binds inside the suspensorium. 
The mandible, as in Siren, is very strong and steep ; its front three fifths is surmounted 
by a phalanx of high flattened teeth ; its hinder part rises high as a rounded boss of 
cartilage, which lies in the deep trough of the strong articulare (ar.), whose angle is 
tuberculate, like the epiotic. 
The steep strong dentary ( d .) reaches nearly to this angle ; the articulare runs far 
forwards ; but the inner face of the mandible shows much of Meckel’s cartilage, unpro- 
tected. Here, unlike other Urodeles, there is no “ splenial,” but there is a rough, 
clubbed bar of bone in front, formed by ossification of the distal part of the cartilage ; 
and although not distinct from the dentary, it corresponds with the “ mento-Meckelian ” 
bone of the wide-chinned Frog. 
This absence of the splenial, and ossification of the cartilage in front, is a second 
point in which this low type agrees with the Batrachia* ; the other was its having no 
“ ascending process ” above the pedicle. 
The hyoid arch also is most anomalous, and but for the ossification of the lower piece, 
would correspond rather with a Shark than with any known Urodele. 
Certain kinds, namely, Siren and Menopoma, have an upper cartilage (hyo-mandibular); 
but in them it is scarcely one fourth the size of that of Proteus, and is partly confluent 
with the suspensorium. 
In the two former types the upper piece is about as much developed as in Ceratodus 
(Huxley, l.c. p. 35, fig. 6, 1LM.). In Proteus it is larger than in Cestracion {ibid. 
p. 42, fig. 8, H.M.) and many times the size of that of JSfotidanus {ibid. p. 44, fig. 9). 
The hyo-mandibular of Proteus {h.m.) is a large, short ray, thick and solid above, but 
scooped on its narrowed, lower part, to form an oblique concavity for the condyloid head 
of the cerato-hyal. The axis of the whole hyoid is parallel with that of the whole 
mandibular apparatus ; the extended top of the hyo-mandibular is attached to the lower 
* Wledersheim: (op. cit. plate 2. fig. 16) gives a splenial to the mandible of Proteus. 
