270 MR. ST. GEORGE MIVART ON THE [Apr. 28, 
oblique one which traverses (in a downward and backward direction ) 
the outside of each hypapophysial arch. This condition is perhaps 
best exemplified in the caudal vertebrae of Chioglossa, where the 
transverse process is in just such a condition as would be one of 
those of the midtrunk of Siren, if its tubercular and capitular parts 
were so reduced as to be mere prominent ridges on the side of the 
centrum instead of strongly projecting, more or less horizontal plates. 
Thus in Siren we have the tubercular process extending downwards 
and backwards from the interzygapophysial ridge and ending in a 
backwardly projecting process, which is also the termination of the 
capitular process, the free edges of the plates forming an angle open 
forwards. Now in Chioglossa we have a ridge (the representative 
of the tubercular part of the transverse process) running downwards 
and backwards from the interzygapophysial ridge, and terminating 
in a backwardly projecting process, which process is also the termi- 
nation of another ridge which runs forwards and downwards from it, 
and is the representative of the capitular part of the transverse pro- 
cess. This latter ridge, as it descends, unites with the ridge tra- 
versing obliquely the outside of the hypapophysial arch, and termi- 
nating behind and below in one of the posteriorly projecting pro- 
cesses of that arch hereafter described. 

Lateral view of anterior caudal vertebrae of Menobranchus (No. 582.4 in College 
of Surgeons’ Museum), 
¢. Tubercular process. c¢, Capitular process. Hy. Hypapophysis. 
Sometimes both the capitular and tubercular parts of the transverse 
process are to be seen distinctly projecting out (though of small 
size) one above the other (fig. 10, c. ¢), from the side of a caudal ver- 
tebra, as e. g. sometimes, at least, in the fourth caudal vertebra of 
Menobranchus. Occasionally a certain osseous connexion exists be- 
tween the caudal transverse process and the hypapophysial arch, or 
caudal hypapophyses. This is the case sometimes in the first one or 
two vertebree of Siren which possess hypapophyses. 
In Menobranchus also a bony connexion distinctly exists, in the 
third and fourth caudal vertebree, between the root of the hypapo- 
physial arch on each side and the under surface of the capitular 
process above it (fig. 15). This shows a certain degree of imperfection 
in the separation of the hypaxial part of the skeleton from the 
paraxial part. 
a 
