Karl Pearson and Adelaide G. Davin 
861 
Meckel does not seem to have examined the Anthropoidea although he deals fairly 
fully with the lesser apes. Gruber has also no data. Owen's paper of 1866 contains 
no reference as to the sesamoids of the knee-joint*. Macalister in his paper on 
" The Muscular Anatomy of the Gorilla "f writes that 
The popliteal muscle had a sesamoid bone or cartilage; it [the muscle?] was about as large 
proportionately as in man. 
Thus Macalister seems the first to have noted the cyamella in the gorilla. We 
have already drawn attention to the fact that Camper had found it in the orang in 
1791. Macalister in a further paper J dealing with the chimpanzee, remarks: 
The popliteus was small aiid had no sesamoid nodule in its tendon thereby agreeing with 
Wilder's and diftering from Vrolik's specimen. Trail did not find it popliteus] present. 
Wilder in his paper on " The Comparative Myology of the Chimpanzee "§ states, 
when dealing with popliteus, that he " could not find the cartilaginous nodule in 
the external lateral ligament where the muscle arises." It is not clear that this 
really does- refer to the cyamella Wilder continues : " Trail and Tyson could not 
find the muscle, but it was present in Vx-olik's chimpanzee and in the gorillas of 
Wyman and Duvernoy" {I.e. p. 375). The "it" of Macalister's sentence just cited 
should refer to popliteus, otherwise Macalister has misread Wilder, who is referring 
to the muscle and not to the sesamoid |]. 
It would seem then that of the anthropoids the gorilla, chimpanzee and orang 
have no fabellae and that gorilla and orang have the cyamella. The chimpanzee on 
the weight of the evidence published above does not seem to have the cyamella. 
Reports that the chimpanzee has it arise from a not unnatural reading of Mac- 
alister's loose wording, at most it can only be as an anomaly. Thus even in this 
respect man approaches more closely to the chimpanzee than to the gorilla or orang. 
By the courtesy of Sir Arthur Keith we were able to dissect the knee-joint of 
a chimpanzee. We found no fabellae, and not a cyamella, but a scarcely perceptible 
thickening of the popliteal tendonll. We procured and dissected the knee-joints 
of two orangs. In neither case was either /aie/Za present but in both cases there 
was a large cyamella : see Plate XXVI, Figs. 68 and 69. Sir Arthur Keith kindly 
allowed one of us to examine his manuscript thesis of 1894 entitled : " The 
Myology of the Catarrhini. A Study in Evolution." It is a most valuable work of 
600 pages presented to the Library of the Royal College of Surgeons in 1919. 
In this work he notes that he has not found the fabellae in gorilla or orang, but 
he found the cyamella (described as sesamoid in the tendon of popliteus above 
* " Osteological Contributions to the Natural History of the Authropoidal Apes, No. vii." Trans. 
Zool. Soc. London, Vol. v. The femora of gorilla, chimpanzee and the orang are discussed on p. 14, 
et scq. 
+ Proc. Royal Irish Acad., Vol. i. 2nd series, p. .50.5. Dublin, 1870, p. 74. 
J "Myology of the Chimpanzee and other Primates," Annals of Natural History, 1871, p. 9. 
§ Boston Journal of Natural History, Vol. vii. p. 375, 1861. 
II Gruber says Vrolik did not find the sesamoid ; and we think Gruber naturally read Macalister's 
sentence to indicate that Vrolik had found the sesamoid and he wished to contradict Macalister. 
H Our chimpanzee was like those of Wilder, Macalister and Vrolik in the fact that popliteus was 
present. 
