18(39.] 81 ICoues. 



the anterior one; while the middle one followed the latter like a 

 simple appendage, in consequence of being bound to it as far as the 

 heel by integument. 



Such were the external appearances presented by this malformed 

 chick. After observing it for a few days I had it killed, in order to 

 examine the internal structure of the anomaly, and found the follow- 

 ing condition of the osseous structures involved. The right leg was 

 normal in all respects ; and so also was the corresponding side of the 

 pelvis. The pelvis as a whole, however, was asymmetrical, the left 

 side being abnormally developed to furnish points of support to the 

 two extra legs. Behind the left ilium proper (which was shorter 

 than the other one) appeared an accessory plate of bone, of an irreg- 

 ularly triangular shape, convex above in every direction, running out 

 in a sharp point laterally ; separated anteriorly by a deep narrow 

 fissure from the termination of the proper ilium, closely joined, if not 

 really articulating with, the vertebrae mesially, and in similar inti- 

 mate relations, inferiorly, with an irregular backward prolongation of 

 the ischium. The latter appeared to be duplicated like the ilium ; 

 but the nature of the ischial redundancy was not clearly made out ; 

 this part of the bone having been accidentally injured before it was 

 seen or suspected to exist. The redundant iliac bone bore upon its 

 antero-external and postero-external aspects, two acetabula, imper- 

 fect, but still well marked and unmistakable, for the movable 

 articulation of the two extra femora ; all three of the left legs thus 

 depending from the haunch-bones in a row, one behind the other. 



Each of the three left legs possessed the normal number, position, 

 shape and relative sizes of the component bones, even to the pha- 

 langes, which numbered on each foot 2, 3, 4, 5, as usual; only the 

 third, or posterior leg was, as has been said, slenderer and weaker 

 than the other two ; and the head and trochanter of its femur were 

 not quite so perfect. The positions of the three legs having been 

 already noted in the description of their external appearance, it only 

 remains to call attention to the very singular characteristics presented 

 by the middle left leg, — the anterior of the two extra ones. 



Close inspection reveals the indisputable and highly interesting fact, 

 that this is, in reality, a leg of the right side, transferred by some 

 strange freak and in a totally inexplicable way, to the left side. 

 This curious fact is susceptible of direct and positive demonstration 

 from the characters of the bones themselves, and is, proven beyond all 

 question. This leg, as has been said, was, when in situ, so far everted 



PBOCEEDINGS B. S. N. H.— VOL. XIII. 6 OCTOBEE, 1869. 



