OF THE SKULL IN THE T7EODELOUS AMPHIBIA. 
573 
edge of a large fascia which runs along from the upper part of the suspensorium, behind 
and beneath the stapes (st.) and is attached to the infero-lateral face of the epiotic (ep.). 
The cerato-hyal is a stout rod, not so thick as the upper piece, and it is invested with a 
strong ectosteal sheath, all but its extremities ; the lower end is bent upwards, and has 
no hypo-hyal segment, another anomaly in this type ; for that is a very constant segment 
in the Urodeles. 
Antero-superiorly, the cerato-hyal is attached by a broad hyo-suspensorial ligament to 
the quadrate, and by a narrow mandibulo-hyoid ligament to the angle of the articulare 
( h.s.l ., m.h.l.). 
Proteus belongs to a small minority of the Urodeles that have no fourth branchial 
arch ; Menobranchus also has only three, and certain lechriodont Caducibranchs, namely 
Spelerpes, have only three, as I find in the larvae of S. rubra and S. salmonea. 
In Menobranchus only the second basibranchial is ossified of all the postmandibular 
structures ; in Proteus only one small segment in the middle of the second branchial 
arch, besides the hyo-mandibular, remains soft. 
The first branchial arch ( br . 1) is very stout; it is normal in having a very long epi- 
branchial and a very short cerato-branchial ( e.br . 1, c.br. 1) ; its pharyngo-branchial, like 
that of the second and third, is represented by its unossified apex. 
The next, much smaller bar is similar, but it has a short, thick, unossified segment 
wedged in between the upper and lower pieces ; to this the third branchial is attached, 
and has no lower piece unless the intercalary segment belongs to it. This inwedged 
piece does not occur in Menobranchus , nor in the Urodela generally ; in that type the 
second cerato-branchial is very small. 
The well-ossified basibranchials are of the same length; but the foremost is the 
thicker by far; its fore end is strongly tied to the distal parts of the hyoid ( b.br . 1, 
c.hy.) ; the hinder piece is not metamorphosed in relation to the larynx. 
This most instructive type thus yields a skull well worthy of being placed between 
the Dipnoi and the higher Urodeles. Of sixteen species of its Order, worked out by 
me, it is the most abnormal. 
On the SJcull of Seironota perspicillata. — First Stage. Larvae ^ an inch long. 
This Caducibranch is one of the smallest I have worked out ; the adult is only 2 inches 
long. It is a native of South Europe. 
The larva, besides coming in well as an intermediate stage between my third and 
fourth stages of Siredon (Plates 22 & 23), has also some important characters of its own ; 
characters not so clearly shown in the fry of the Axolotl. 
The adult, also, carries the Salamandrian modification of an Amphibian skull to the 
highest level, the finish of the cranial building being very perfect, and analogous to 
what is seen in the skull of the higher Batrachia, and even in the Reptiles. 
The larval skull (Plate 29. figs. 1, 2) shows what, a year or two since, Professor 
Huxley considered to be a thing not known, namely, the perfectly distinct chondrifi- 
cation of the parachordals (iv.) behind, from the trabeculse (tr.) further forward. 
