390 
On the Sesamoids of the Knee- Joint 
Our third dissection was of a knee-joint of Amphibolurus barbata. Here we have 
no longer the parafibula, but posterior mesial and lateral lanulae, mesial anterior 
and lateral (or rather sagittal or trochlear) anterior lunulae (see our Plate XXIV, 
Figs. 65 0 and 656). In this case the lateral posterior lunula is larger than the mesial, 
and there is a groove on the trochlear portion of the femur — exaggerated in the 
drawing to indicate its existence — which probably articulated with the sagittal 
lunula. In a very young specimen of Iguana tuberculata (Lacertilia) we were 
unable to find any parafibula ; the posterior lateral lunula and the anterior sagittal 
lunula were present*. Mivart, who has studied the myology of Iguana tuber culataf, 
states that the outer head of gastrocnemius in this case arises from above the 
external condyle, that plantaris is very intimately connected with gastrocnemius 
and that popliteus arises from the fibula. He makes no mention of a parafibular 
sesamoid. In considering the absence of the parafibula this arrangement of the 
muscles should be borne in mind. 
Specimens of Agama stellio and of a common lizard (Lacerta vivipara) dissected 
in our laboratory confirm the arrangement in Varanus of a parafibula with two 
anterior and two posterior lunulae. 
In a specimen of Spenodou punctata examined no parafibula was found but only 
an anterior sagittal (mid-trochlear) lunula. This was confirmed from a mounted 
specimen of Spenodon seen at the South London Botanical Institute. 
Mounted skeletons of the Reptilia do not as a rule afford much information, 
either when large on account of being over clean, or when small the knee-joints being 
often inaccessible even with the use of a lens to minute examination. They require 
dissection when moist. We may note the following observations made chiefly on 
specimens at the Royal College of Surgeons. 
We examined three chameleons. In Chamaeleo vulgaris, we found a sesamoid 
at the top of the fibula and between this and external face of lateral condyle; there 
were no lunulae (or, of course, fabellae); the patella was ossified. In a specimen of 
Chamaeleo verrucosus there were cavities from which it looked as if parafibular 
sesamoids had fallen out. In a specimen of Chamaeleo bifurcatus nothing was dis- 
tinguishable. In Zonosaiirus madagascarensis there was an ossified patella, but no 
other visible knee-joint sesamoid. In Eumeces algeriensis there was a parafibula 
wedged between fibula and tibia ; we also found a single lunula. 
In Corucia zebrata there was a somewhat noteworthy system of knee-joint 
sesamoids. There was a sesamoid articulating with the head of the fibula and 
a second, directly connected by a ligament with the first, articulating with the head 
of the tibia ; it would be easy to interpret either or both as cases of lunulae : see 
drawing, Plate XXXV, Fig. 91. There was a small ossified patella. Parafibular 
and paratibial sesamoids also occur in Lacerta ocellata together with an internal 
anterior lunulaX- 
* In a mounted specimen of I. tuberculata, we again found no parafibular sesamoid, but the anterior 
lunula was rather lateral than sagittal. 
t Proc. Zool. Society of London, 1867, p. 795. 
J This lizard had, but on the left limb only, what looked like a possible lateral fahella. 
