Karl Pearson and Adelaide (i. Davin 
387 
case of any fibres of the mesial head of gastrocneinius being attached to the semi- 
lunar. Such cases may, however, exist. 
(21) Birds. 
We have not examined a hirge number of birds' pelvic limbs, but we have not 
found in any of the cases we have examined nor in mounted skeletons Q\\ih.(iv fahellae 
or cyamella. On the other hand we have found luinilae, for example, in Syntitna 
stridula (the Wood Owl) and Dendrocygnn (the Tree Duck), the latter having in our 
specimen at least three posterior lunulae. The tibia of this bird also possesses 
a marked cnemial crest (see Plate XXII, Figs. 52, 53 and 54) apparently articu- 
lating with a small patella ; this crest reaches to the level of the top of the patella. 
In Divers, Grebes, Albatrosses (see Plate XXII, Figs. 50 and 51), etc., this crest 
formed from an extension of the middle and internal crests of the tibia becomes 
a still more emphasised process and can even be as long as the femur itself*. 
The homologue to the tibial crest appears to be the olecranon of the ulnaf. 
Owen has noted in certain birds an ossiculum beloncring to the ulna which he 
states is " essentially the separated olecranon of that bone. This detached sesamoid 
bone is found attached (like the patella of the knee-joint) to the capsular ligament 
and the tendons of the extensor muscles in many of the Raptores and in the Swifts. 
In the Penguins it is double j." It would seem more justifiable to compare the 
cnemial crest of the tibia with the olecranon than the latter with the fibular 
process of the Monotremes, and not unreasonable to suppose that if the olecranon 
can give rise to sesamoids, a similar change can take place in the cnemial crest. 
In Apteryx australis there is a semi-cnemial crest surmounted by a cartilaginous 
patella. It is true that in some birds we know with marked cnemial crests the 
patella still exists, partly articulating with the femur and partly with the cnemial 
crest, but in Colymbus it is reduced to a " flake-like bone§." The patella, as we have 
remarked, has been associated with the olecranon by Vicq d'Azyr[|. Shufeldt, 
while associating the olecranon with the cnemial crest, looks upon the patella as 
not arising from its partial break-up, but treats the patella as a sesamoid. 
We have carefully studied the evidence given by Shufeldt^, but it seems to us 
quite as capable of interpretation in favour of the patella being originallj^ the part 
or whole of the cnemial crest, as of both having quite distinct and separate origins. 
He first cites the great diversity of patellar forms in birds, from its absence in 
certain species, as Haemotapus iviger, to the small double almost cartilaginous 
* According to Owen its importance arises from the j^rovision it affords for extensive attachments by 
way of insertions for the extensors of the tibia and by way of origin to the extensor of metatarsus. Thus 
the power of the back stroke of the foot is increased: see Todd's Cyclopaedia of Anatomij and Physiology, 
Vol. I. p. 287. 
t Coues writes of Colyinhug torquatus (loc. cit. on our p. 392) that the tibial crest exactly resembles 
the olecranon of the human species (p. 158). 
J Owen's article Aves in Todd's Cyclopaedia, Vol. i. p. 286. 
§ Of Colymhm septentrionalis {Red-throated Diver) we have examined two skeletons, but found no 
signs of a, patella, although the semi-lunars were in nidi. 
II Histoire de V Academic Roy ale des Sciences, Paris, 1774, p. 2()1. 
11 "Concerning some of the forms assumed by the Patella in Birds," Proccedinys U.S. National 
Museum, Vol. vii. pp. 324—331, Washington, 1886. 
