854 
On the Sesamoids of the Knee- Joint 
Rangifer tarandus (reindeer, 2 cases), Tragidus javonicus* (moose deer, 3 cases), 
Gervus elwplms (red deer), Connochaetis gnu (white tailed gnu), Alces machlis (moose 
or elk), Cervus davidianus (David's deer), Gervus puda (Puda deer), Hyomoschus 
aquaticus (African chevrotain), Gervus capreolus (roe, 2 cases), Hydropotes inermis 
(Chinese water deer), Strepsiceros kudu (koodoo), Auchenia pacos (alpaca), Auchenia 
vicugna (vicugna), Sus scrofa (Indian wild boar, 3 cases), Dicotyles lahiatus (white 
lipped peccaiy, 2 cases), Phacocliaerus africanus (Aelian's wart hog), Hippopotamus 
amphibius (2 cases), Baird's tapir, Equus zebra, Equus asinus, Gamelus bactrianus, 
Gamelopardalis giraffa (Nubian giraffe), Elephans indicus, Rhinoceros unicornis, 
Rhinoceros sumatrensis, Bos taurus and also Equus caballus, Orlando (the thorough- 
bred race-horse) and numerous other ungulates. 
In the face of the large number of skeletons of Gervidae examined, it seems 
hard to believe that the external fabella has been removed in all these cases, i.e. 
that it can be, as Meckel asserted, universal in Gervus-f. 
We have dissected a specimen of a young Tragulus, probably from Malasia, but 
found no fabellae nor indeed any sesamoids of the knee-joint. In our opinion an 
indication of the ancestral history. 
Apart from Gervus, Hyrax is the only ungulate with sesamoids of the knee- 
joint. According to Blainville both fabellae are present, but Meckel and Brandt 
credit it only with the external fabella. We first examined two skeletons. On one 
Hyrax dorsalis, there was no trace of a fabella left, if there ever had been any ; on 
the other Hyrax capensis, there was a small external fabella. Murie and Mivart 
in their "Myology of Hyrax capensis l" describe gastrocnemius, plantaris and 
popliteus, but do not refer to any sesamoids. We were able to examine further one 
knee-joint of Hyrax with certain of the muscular attachments (see Plate XX, Fig. 45). 
Unfortunately the popliteal tendon had been cut short before it passed over the 
fibula so it is impossible to say whether a cyamella ever existed. The external 
fabella was present, but gastrocnemius had shrunk in drying, so that the sesamoid 
was lifted off the external condyle. There is a slight depressional facet on the 
articular surface of the internal condyle suggesting the possibility of a mesial 
fabella. There is, however, no doubt about the existence of the external fabella. In 
another mounted specimen of Procavia, we have found not only the external fabella, 
but an external anterior lunula. These facts provide at least suggestions for the 
reclassification of the Hyracoidae. Apart from the Gervidae and Hyracoidae — 
where the presence of the external fabella may throw light on their evolutionary 
history — we are forced to the conclusion that the large (and mixed !) order of the 
ungulates presents no sesamoids of the heads of gastrocnemius or popliteus. The 
absence of the fabellae in ungulates has been frequently noticed^, but so far we 
believe no stress laid on its evolutionary importance. 
* We failed to find any sesamoid of the knee-joint on dissecting a young Tragulus : see below, 
t On the fossil Megaceros hibernicus (Irish deer) we were unable to find any trace of a fabella. 
J Proc. Zool. Society, 1865, p. 350. 
§ Meckel, Gruber, etc. See also Journal of Anatomy and Physiology, Vol. xxxii. p. 750, 1898. 
