356 
On the Sesamoids of the Knee-Jomt 
Fteropus — having the muscles attached, but we have failed to find any sesamoids. 
It is probable that a microscopic examination of sections from moist material would 
lead to more conclusive results, and, perhaps, indicate minute patches of hyaline 
cartilage hardly appreciable by ordinary dissection. For our present purposes, 
however, such an investigation would be very unlikely to change the significance 
which can be drawn from the results for Chiroptera. In this order the sesamoids 
of the knee-joint appear occasionally, as in the higher primates, or in minute forms 
and are vestiges of a complete system of patella, fabellae, and cyamella, which be- 
longed to their evolutionary ancestors. Even in this case which is merely vestigial, 
it is worth while noting the greater importance of the external fabella. 
(13) Insedivores. 
With this order we reach vestiges of a more primitive state of affaii's in the 
sesamoids of the knee-joint. The liinulae common in the Rodents and carrying us 
back to reptilean forms are frequently preserved. In the carnivores and the higher 
primates they occur only as anomalies or have disappeared entirely. According to 
Blainville* all insectivores have both fabellae. Owenf qualified this by saying that 
most insectivores have both. Meckelj had already remarked that the mole has both 
fabellae, but the hedgehog he reported as having only the external fabella. Gruber§ 
on the contrary found the mole to have an external fabella only. He reports that 
both fabellae are wanting in Erinaceus europaeus and E. auritus, and again in the 
shrew mouse, both Sorex vulgaris and S. fodius. He examined three cases of 
Myogale moschata, the Russian desman. In the first case there were no fabellae ; in 
the other two cases no internal but external fabellae. 
In den Fallen aber mit Vorkommen des Ossiculum externum sass dieses in eineni Ausschnitte 
am Ende des scharfeTi Angulus extern us iiber dem Condj^lus externus und daneben in einer kleiner 
Grrube an der hinteren Fliiche dor Fenuir||. 
In the case with no fabellae there was a " platter Fortsatz " on the same spot. 
Gruber found this also in Myogale pyrenaica where there were no ossicles. We 
dissected two moles, Talpa europaeus, and found the external fabella only; thus our 
specimens agreed with Gruber's and not Meckel's. The hedgehog {E. europaeus) 
examined by us had both fabellae and both lateral and mesial anterior lunulae (see 
Plate XXIII, Figs. 56a and 5{jb). Thus Gruber's statement is not universak In a speci- 
men of Myogale moschata we found only a large external fabella of unusual shape and 
size, and in Myogale pyrenaica no fabellae ; these two latter in mounted specimens 
only. In mounted specimens we found only a large external fabella in Talpa euro- 
paeus, Macrosceledes (elephant shrew), Solenodon cubanus and Tupaia javanica. In 
a specimen of Tupaia picta in our laboratory both fabellae are present, and both 
occur in Tupaia tana, the Borneo tree shrew. We have also found both fabellae in 
* Ostiographie des mainiiiijeres, Tom. i. Fasc. 4, p. 47, Paris, 1841. 
•f Anatomy of Vertebrates, Vol. ii. p. 393. 
J Loc. cit. S. 634. § Loc. cit. p. 56. 
II Gruber notices {loc. cit. p. 64, that tlie externa} fabella in Myogale is sometimes fused to femur in 
a special Fortsdtzchen. Tliis is the only reported case of ankylosis of a sesamoid we have come across, 
except in the Marsupialia. 
