On the Sesamoids of the Knee- Joint 
Gyamella in Man. It is very much less easy to differentiate the cyamella by 
aid of skiagraphic analysis. As it lies deep in the popliteal sulcus, it can hardly 
be distinguished by a norma lateralis of the knee-joint. A norma frontalis pro- 
vided the cyamella is of considerable size ajipears to give the best chance. Thus 
Plate XI, Fig. 25 provides an illustration of Avhat is probably a cyamella lateralis. 
Plate X, Figs. 22 and 23 shows another cyamella lateralis from posterior and frontal 
aspects. Plate XI, Fig. 24 gives our nearest approach to a cyamella mesialis. 
There is something similar in Figs. 22 and 23 of Plate X. We decline to interpret 
them and should refuse entirely to be dogmatic about them. But taken in con- 
junction with Pfitzner's statement as to what he had found in two cats (see our 
p. 1C4), we think it important that in the dissecting-room, the skiagraphic studio 
and the laboratory of comparative anatomy the investigator should bear in mind 
the slight possibility of a mesial cyamella*. We have found two probable and 
one doubtful lateral cyamellae in our 352 cases, or in 0-57 of cases probably and 
in 0'85 possibly. Thus the cyamella. la.teralis in man first recorded by Macalister 
appears to be of great rarity. 
Lumdae. Our search for these sesamoids so common in lower types was not 
very successful. In the first place the skiagrams do not exhibit ossifications of 
the semi-lunar cartilages at all clearly, and in the next pathological ossifications 
of the semi-lunar cartilages appear to be far from infrequent. Plate XII, Figs. 26, 
27 and Plate XIII, Fig. 28 indicate what may be true ossicles of the semi-lunar 
cartilages. In the case of Fig. 27 the lunula is accompanied by what may possibly 
be an ossicle on the antero-lateral border of the tibia immediately above the 
capitulum fibulae. On the whole we found nine lunulae ranging through various 
shades of doubtfulness. Thus the occurrence of lumdae in man does not exceed 
2*5 of knee-joints and is probably far less. 
We have not included the patella in our consideration of the knee-joint 
sesamoids, but in examining these skiagrams we have found apart from obvious 
pathological cases five or six of double patellaj-. We are prepared indeed to be 
told that even these six are pathological ossifications of the tendon of the 
quadriceps. But we are not equally certain that those who will take this view 
are fully aware of the regular occurrence of the double patella in certain lower 
types. Tillmans and Bernayst have found in man in several cases a hemi- 
sesaraoidal body above the true patella and Bernays notes the same conditions in 
some of the Felidae and the rodents (Cat, Mouse, Rabbit). Pfitzner found such a 
double patella in the Leporidae (loc. cit. S. 577). In this consideration it is worth 
noting that Macropus giganteus has a hemisesamoid instead of an orthosesamoid 
* In the first and last cases an anatomical preparation should certainly be preserved of any discovery 
or supposed discovery. Our own case is not so definitely an osteome as Gruber's : see our Plates X and 
XI, Figs. 22—24. 
t No percentage is possible as the, anterior and posterior views of the knee-joint give no power of 
discriminating a Aonhle patella. 
X "Die Entwicklungsgeschichte des Kniegelenkes," Morpliologhcltes Jahrbuch, iv. Supplement, 1878, 
S. 442. 
