28 
flexor longus pollicis. This compound muscle, occupying the whole 
posterior surface of the bones of the leg, so pushes round the tibialis 
posticus, that it takes the chief part of its origin from the inner side 
of the tibia, which in Mammalia generally is free from muscular 
attachment. In the Paradoxurus I found that the flexor longus 
digitorum has, in addition to its usual attachments, a point of origin 
in the head of the fibula; but then the bones are separate, and the 
flexor longus pollicis is a distinct muscle, having also origin in both 
bones, and each tendon passes the ankle in its usual place*. 
March 13, 1849. 
W. Yarrell, Esq., Vice-President, in the Chair. 
The Secretary reported that a living specimen of Herpestes fasciatus, 
Desm., and Celogenys paca, Linn., had just been added to the So- 
ciety’s collection. The former animal was exhibited to the Meeting. 
The Secretary directed attention to a small series of skins of Mam- 
malia and Birds collected in Ceylon and Sennaar by Aubrey Paul, 
Esq., the species of which were briefly noticed by Mr. Gray and 
Mr. Gould. 
The following papers were read :— 
1. NoTice OF A PECULIARITY OF STRUCTURE OBSERVED IN THE 
AorTA OF THE Witp Swan. By Joun Davy, M.D., F.R.S. 
L. & E., Inspecror-GreNERAL oF ARMy HospirTaLs, ETC. 
(Communicatep By Mr. GuLLIVER.) 
When engaged in examining anatomically this bird (a full-grown 
female, killed in the neighbourhood of Chatham in February 1839), 
my attention was arrested by a peculiar appearance in the inferior 
portion of its aorta, which I shall briefly describe with the hope of 
leading to further inquiry. Before the ischiatic arteries are given off, 
the aorta is comparatively large and is enveloped externally in a dense 
fibrous coat, possessing very little elasticity : below the origin of these 
* Since writing the above I have taken opportunities of looking at the same 
muscles in a Fox and in a Monkey (Cercopithecus pygerythrus). The former animal 
differed from the Paradoxurus, and resembled the Jerboa, in the great extent of the 
flexor longus pollicis and the much-reduced size of the tibialis posticus, which here 
also terminates in a long slender tendon, showing an interesting correspondence of 
adaptive character in two animals, in which the motion of the hind-limbs is vi- 
gorous, but of one kind only. In the Monkey the flexor longus pollicis is a much 
larger muscle than the flexor longus digitorum, and has considerable attachment 
to the tibia. 
Meckel and Cuvier allude to the union of the two long flexors in the Rabbit 
Nee they pass the ankle, but neither author informs us at which point that takes 
place. 
