298 
usually limited to the phalanges. 
BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Such conditions have been described 
by Struthers (63), Arloing (67), and Boas (’85). 
B. OBSERVATIONS. 
Through the kindness of Dr. Frothingham, of the Harvard Veterinary 
School, an abnormal manus of a polydactyle colt came under my observa- 
tion. 
mt carp. 
= Pier. 
phat. 2” 
2 pit. 3° 
Fic. Z.— Anterior view of left poly- 
dactyle manus of the horse, showing dupli- 
cation of digit 11. mt’carp., distal end of 
third metacarpal bone; phz. 1, first phalanx 
of third digit; phx. 24, 25, duplications of 
second phalanx; pha. 34, 3%, duplications 
of ungual phalanx. 4 natural size. 
flexor perforans were duplicated at their distal ends. 
The specimen came from Texas. 
Externally the hoof was almost 
completely divided into two; each 
portion was several inches long, and 
curved away from the other. On ex- 
amining the skeletal parts (Fig. Z), 
they were found to be normal down to 
the distal end of the first phalanx, 
which was bifurcated and bore two 
articular surfaces. Hach of these car- 
ried two phalanges, which resembled 
the median and ungual phalanges 
of the artiodactyle digit. The two 
series were mirrored images of each 
other ; each os pedis was slightly con- 
cave on the surface facing the median 
plane of the digit, and convex on the 
opposite side, so that the two fitted 
together would give a phalanx of 
nearly normal form. A navicular of 
about half the length of the normal 
bone articulated with the posterior 
face of each os pedis, thus resembling 
the condition of ruminants. 
This specimen had been dried be- 
fore it was examined, and the inner- 
vation could not be studied, but ex- 
amination of the chief muscle tendons 
showed that the extensor pedis and 
This case is there- 
fore simply an example of duplication of digit 111. 
It has long been known that the “splint bones” of the equine manus 
represent rudimentary metacarpals, but until recently the presence of 
phalangeal vestiges in the manus of the embryo has been denied. 
