372 
On the Sesamoids of the Knee- Joint 
Hypsiprymnus, which has no mesial fabella, but (according to G.) a large 
lateral fabella articulating with external condyle*, and no sesamoid in the 
popUteus ; and : 
Halmaturus where (according to G.) both fabellae exist ; the lateral articulates 
with external condyle and is united to tendon of gastrocnemius, but it had also a 
short ligament to the external semilunar. It was " hornformig." 
We failed to find a mesial fabella in two specimens of Halmaturus (sp. ?). The 
species of Halmaturus is also not stated by Grubei-. 
According to Meckel Halmaturus (sp. ?) has only the lateral fabella and the 
same statement is made by Pandir and d' Alton for the species H. elegans and 
H. giganteus. 
The only other record of a mesm\ fabella^ in the marsupials that we have come 
across is due to Windle and Parsonsf, discussing the anatomy of Macropus rufus. 
They state that the inner head of gastrocnemius had also in the older specimen a 
fabella of much smaller size than that of the outer head and differently situated. 
" This fabella lies below the origin of the muscle from the back of the condyle of tbe 
femur and between the muscular fibres and that bone upon which therefore it plays." 
We have examined a considerable number of mounted specimens of Macropus, 
the lateral sesamoid was almost invariably preserved but we have failed in any 
case to find a niesial orthosesamoid preserved J. It is possible that the articulator 
in all these cases overlooked the smaller me^iiaX fabella, but it is equally conceivable 
that the mesial fabella in Windle and Parsons' case was a hemisesamoid§. 
Before discussing further other contributions to our knowledge of the knee-joint 
in the Marsupials, we wish to draw the attention of the reader to Plate XXIX, Fig. 
78. The photograph on the right exhibits the lower limb bones of Phascolomys, the 
wombat. In this specimen there are no sesamoids at all, the large lateral sesamoid 
is seen as a fibular crest and is fused to the bone. The femur articulates with both 
tibia and fibula, and the head of the fibula comes in contact with the femur 
above the lateral condyle where the lateral fabella is often placed by the articu- 
lator. The limb to the left of the plate is that of Sarcophilus, the Tasmanian Devil. 
Here again the femur articulates with both tibia and fibula. The fibula has a para- 
fibula precisely like that of Phascolomys. The summit of the fibula touches the 
femur above the lateral condyle, and there may even be a pit (as in the sea-otter ; 
see our Plate XIX, Fig. 40) for its reception ||. The reader may say : " But this is the 
large external fabella of the marsupial myologists." It is and it is not ; it really 
consists of two sesamoids, the lateral fabella and the cyamella; they are in this case 
fused together and fused, to the head of the fibula. 
* Confirmed by us on au articulated specimen of Hi/psipri/miius murhius. 
t Journal of A natomy and Phiisiologi/ , 1897, p. 128. 
f Macropus rufus, Macropus (sp.), Macropus agilis, Macropus major, Macropus benncttii, etc. 
§ At the same time we note that without finding a mesial fabella, we bave found a cartilaginous 
thickening — hardly a hemisesamoid — in a specimen of Macropus agilis and in one of Dendrolagus, the 
tree kangaroo. 
II As for example in the mounted specimen in the British Museum (Natural History). 
