314 PEOrESSOE OWEN ON THE EOSSIL MA30L\LS OP ATSTEALIA. 
auditoria interna pierce the bone. On both sides the t^-mpanic sinuses in the alisphe- 
noid 6 , are exposed; and their concordance with those m the Dasyun is veiT clearly 
exemplified on the left side, in which the tympanic bone, 28, is preserved, shou^g its 
characteristic shape and relative position behind and external to the alisphenom 
^ The canal of the meatus {Ic) external to the tympanic, is excavated in the outwardly 
produced base of the zygoma, behind the postglenoid process (Z), for an extent resem- 
bling that in the Basyuri, but much greater than in the Dog or other placenta 
Another character distinctive of the marsupial order is the position of the entocarotid 
canal (m), which perforates the outer and back part of the basisphenoid, 5* ; this o^ce 
is lodged in a fossa between the basioccipito-sphenoid and the bulla auditoria m Thy a- 
cinm and Basyums {ih. fig. 2, m), and it presents exactly the same position, and per- 
forates the same part of the basisphenoid, in Thylacoleo. 
Ill the genus Felis the entocarotid enters the base of the skull at the tore-part of the 
foramen jugulare, notching the part of the petro-tympanic bulla at the fore-part of that 
foramen. In the Hyeena, as in the Viverrines, the entocarotid notches or peifora es 
the tympanic bulla in advance of the jugular foramen close to the ^de ol t e asi- 
occipital: it perforates the same part of the tympanic bulla in the Otter and ochex 
Mustelines. . _ , ^ 
The foramen ovale pierces the base of the alisphenoid immediately anterior to t.. 
bulla in the marsupial Camwora, and is divided by a ridge from the caintid canal m 
the Kaswri ; it presents the same relations in r/iyfacofeo (Plate XI . g. .»)•““ 
base of the ridge (ib. s) also remains to show the existence of that ch^acter. 
The interval between the foramen ovale (Plate XI, fig. 1, n) and loramen rotimdum 
(ib. p) is relatively much gieater in the marsupial than in the placental Canm-om In 
the genus Felis, they are separated from each other only by the base of the in gc or 
rising of bone extendmg from the ectopterygoid towards the glenoid cavity, and the 
foramen is on the same transverse line with the anterior bomidaiy oi that articulation , 
in the Hy®na, Viverrines, and Dog, it is a little in advance of the same botiiidary ; m the 
Otter it opens externally into a fossa common to it with the torainen laceniin ame.un 
(or for. ophthalmioum). In the Thylacine and Dasjnres the foramen rotundum is distinct 
both within and without the cranial cavity from the foramen lacenmi anteriiis. audits 
far in advance of the glenoid cavity. It presents the same relative position in tnc 
I7(»(aco(co (Plate XI. fig. 
In Felis the foramen rotundum is larger than the foramen opticnin , in , J < . 
it is much smaller; and this is the case also with the Thylacoleo (Plate XI. fig. )• 
although the foramen opticum (y) is relatively smaller than in the Vasyucus Ursulas. 
. ..The carotid canals pierce the body of the sphenoid, as in BW*;, 
together behind the eella t„reico.’'-ZoologlcaJ Transactions, vol. ... (Oetobe.-, 1S3S) p. 390 .ee 
ir— s eareW and .ninnte account of the ..Porainina at the Base of the Skull" ,n Zoological Pro- 
ceedings, May, 1848, p. 64. 
