396 
On the Sesamoids of the Knee- Joint 
DESCRIPTION OF PLATES XIX— XXXVII *. 
Plate XIX, Fig. 40. Femur of Sea Otter (Enhydr.i lutris), showing the marked development of the 
lateral fahcUa ; the sesamoid appears by its action to have largely eroded the popliteal surface of the 
femur, and the periosteum of the bone in its neighbourhood has disappeared. 
Fig. 41. Fibula, Tibia and Femur of Beaver (Castor fiber). The development of the fibular head at A 
suggests how a second sesamoid might well originate in the tendon of the muscle (Peroneus longus ?) 
attached to this projection. The femur exhibits a marked third trochanter. 
Plate XX, Fig. 42. Drawing of musculature of knee-joint of Oraithorhynchus . We see the lateral 
head of M. gastrocnemius attached solely to the fibular crest ; the mesial head of gastrocnemius is still 
attached to the mesial condyle. 
Fig. 43 a, anterior, and Fig. 43 6, lateral aspect of the femur, tibia and fibula of Ornithorhynchus. 
The fibula shows the noteworthy crest, a compressed process with its own centre of ossification. There 
are no sesamoids except patella. Cf. Fig. 47 for the corresponding bones of Echidna. 
Fig. 44. Drawing of the posterior aspect of the left knee-joint of Felis domestica, showing the 
positions of the external (e.f.) and internal (i.f.) fahellae, the cyamella (cy.) and the facet on which the 
latter rests. Owing to the knee-joint being slightly extended the cyamella has been lifted oil its articular 
surface on the head of the fibula t- 
Fig. 45. Drawing of postero-lateral aspect of the left knee-joint- of Hyrax showing the external 
fahella (e.f.) above the external condyle, but the tendon of gastrocnemius has shrunk in drying, so that 
the fabella has been lifted off the condyle. There is a slight depression on the internal condyle, which 
might suggest an internal /afcc/Za, but so far none has been found. 
Plate XXI, Fig. 46. Colymhus glacialis, a drawing after Owen's figure in his article Aves in Todd's 
Cyclopaedia. Note the remarkable cnemial crest of the tibia. Cf. esijecially all the figures on Plate 
XXXVI. 
Fig. 47. Lateral aspect of pelvic limb of Echidna to be compared with the knee-joint of Ornitho- 
rhynchus in Figs. 43 « and 43 i. Drawing after a part of the skeleton in a plate of Cuvier's Recherches 
sur les ossemens fossiles, Paris, 1834-6 (Tome ii, Atlas Plate 214). 
Fig. 48. Drawing of lateral. Fig. 49, drawing of mesial, aspect of knee-joint of left limb of Cereopsis 
Goose, showing cnemial crest of tibia and also a semi-fibular crest which works in a groove on the 
articular surface of the lateral condyle. Cf. Plate XXXVI. 
Plate XXII, Figs. 50 and 51. Drawings from lateral and mesial aspects of the left knee-joint of the 
Albatross, showing the remarkable cnemial crest of the tibia. 
Figs. 52, 53 and 54. Drawings of anterior, lateral and posterior aspects of knee-joint of Dendrocygna, 
the Tree Duck. There is a cnemial crest (cn. crest), internal (i.p.lu.) and external (e.p.lu.) posterior 
lunulae and also what appear to be two or three very small sesamoids wedged in between fibula and tibia 
(sesamoids). Cf. Plate XXXVI. 
Plate XXIII, Fig. 55 a. Tamandua Anteater (Tamandua tetradactyla) ; photograph of posterior 
aspect of right limb showing the large cyamella (c.) still in the popliteal tendon. 
Fig. 55 6. Common Squirrel (Sciurus vulgaris), photograph of posterior aspect of right limb, showing 
internal and external lunulae (i.l. and e.l.) and cyamella (c). Both fabellae also exist in the squirrel. 
Figs. 56 (( and 56 b. Common Hedgehog (Erinaceus europaeus). The former photograph of posterior 
aspect of right limb showing internal (('./.) and external (e.f.) fabellae ; the latter photograph of mesial 
aspect of left limb with the femur doubled right back to show anterior external (a.e.l.) and anterior 
internal (a.i.l.) lunulae. No cyamella was found. 
Fig. 57 a. Photograph of the right pelvic limb of Hydromys chrysogaster, the Golden-bellied Eat, from 
the posterior aspect showing internal (i.f.) and external (e.f .) fabellae . 
* The drawings are as a rule natural size. 
t It must be remembered that in nearly all these drawings the sesamoid bones are still contained in 
the tendons in which they occur. Consequently no attempt could be made to show the actual size of the 
sesamoids. 
