Karl Pearson and Adelaide G. Davin 
351 
orthosesamoid will be found to exhibit this prefiguration if the knee-joint be 
examined in the embryonic or early post-natal states. 
Two points of much bearing on what follows later were reached as the outcome 
of these investigations : 
(a) The cyamella of the rabbit was found near the head of the fibula, there 
was no marked popliteal groove for it to lie in. 
(6) The lateral and mesial fabellae while both prefigured by hyaline cartilage 
in kittens were very unequal the former being far more developed. Pfitzner* says 
that he found the fabella medialis absent in 29 cases out of 52 in the cat. He 
states that it always occurs in dog, fox and hare. Meckelf states that both in cat 
and dog only the external /a6eZ/a occurs. GruberJ places Canis familiaris (as well 
as C. vulpes and G. lupus) and Felix domesticus in the group which have both 
fabellae. Thus he tells us that in puppies at birth he found hyaline cartilage and 
later orthosesamoids ; the external ossified first at about six months. The extei'nal 
fabella articulated with the femur in a trough (" Grube ") with projecting rim on 
the upper part of the external condyle of the femur ; the internal fabella was in a 
less marked trough on the upper part of the internal condyle. With regard to 
newborn kittens both fabellae were prefigured by hyaline cartilages : the external 
ossified first and the internal was smaller and of a different shape. 
(9) Carnivores. 
While our experience with kittens accords with that of Gruber, and not with 
that of Pfitzner, and while we have found the two fabellae in many adult dogs, 
we have not invariably found the mesial fabella after most careful sectioning of the 
tendon of the internal head of gastrocnemius in puppies of a fortnight old (failed 
in two cases). On a general balance of the evidence therefore we are inclined to 
believe that cases do occur in the smaller carnivores, in which both fabellae are not 
present, although Meckel's view that only one occurs in dog, cat and fox is certainly 
incorrect. 
While dealing with the carnivores we may note that Gruber examined a female, 
aged one year, of Felis leo, and found an external hemisesamoid, the internal was 
represented by a pad (" Wulst ") with no cai'tilage cells {loc. cit. p. 59). Further in 
Gulo vittalus there was an external fabella only, which as in man did not articulate 
with the fennir, but lay in the tendon of gastrocnemius, and between that and the 
knee capsule (p. 57). Further the external fabella and that only has been found 
by Gruber in Nasua, Ursus arctos, Mustela alpina and Lutra marina. Blainville 
found none in Ursus, Meckel found the external only. The latter found the external 
only in Feliw lynx, the raccoon, and the hyaena§, while Blainville and Owen found 
both in the hyaena; and Meckel found both in Mustela and Lutra. Davisjj and 
* See work cited {Biometrika, Vol. xiii. p. 163), S. 582. 
t System der vergleichendcn Anatomie, S. 634, 635, Halle, 1828. 
t See work cited (Biometrika, Vol. xiii. p. 156), pp. 57, 58. 
^ Loc. cit. 8. 634—635. 
II Journal of Anatomy and Pliyxioloyy, ISi^S, p. 215. 
