215 
into a fossa which contains the foramina of the orbit ; pterygoid 
bones with their hamular processes styliform, projecting backwards ; 
zygoma small, rounded above ; tympanic incompletely ossified ; mas- 
toid bone broad, placed obliquely ; lower jaw slender, its condyle 
elevated, reniform ; coronoid process feebly developed, lower than the 
condyle. 
X. UNICINCTUs. 
Cuvier mentions a species with a shorter and more entirely naked 
tail; it is probably the same that has been called nudicaudis by Dr. 
Lund. X. antiquus of the same distinguished author may possibly 
be identical. 
Priopontes, Frederick Cuvier. 
Head broad behind, ears wide apart ; plates of the head and body 
as in Xenurus ; tail closely covered with quadrangular scales, placed 
im a quincuncial arrangement ; fore-feet as in Aenurus, the outer toe 
much reduced ; maxillary bone articulated posteriorly by suture to 
the palatine; teeth numerous and minute ; infra-orbital canal long, 
commencing below the malar process, and terminating nearly on the 
middle of the bone; malar bone forming simply a portion of an in- 
verted arch, round, and devoid of processes ; palatine bone ascending 
into the orbit ; pterygoid bone strongly developed, with an angular 
termination ; zygoma .rather small, the glenoid surface lengthened, 
the lower part of the Squamous and the alisphenoid bone forming a 
longitudinal swelling within it; tympanic bone small, and loose ; 
mastoid bone broad, forming the sides of the occiput which are 
rounded ; lower jaw thin and compressed, condyle longitudinal, but 
little elevated ; coronoid process much reduced. 
P. gigas. 
Totyreures, Illiger. 
posed of oblong parallelograms, equally subcireular, and closely arti- 
culated; fore-feet four-toed, the outer being absent; the medius 
slightly longer than the index, with a much larger claw, both having 
and simply abutting by an oblique suture against the zygoma ; _pala- 
tine bone ascending into the orbit, pterygoids with blunt hamular 
