1886. ] GEOCOCCYX CALIFORNIANUS. 483 
admirably hold the several groups of flexor tendons in place, and at 
the same time they act as pulleys for their guidance and afford 
correct application of the force intended to flex the toes. 
The flexor longus hallucis (Plate XLIV. figs. 2, fil; Plate 
XLV. figs. 1, 2, £1.) has two separate heads, the one coming off 
from the outer side of the external condyle of the femur, and the 
other, far more fleshy, arising from the posterior aspect of the same 
bone between the condyles. Above this muscle is overlapped by 
the more superficial flexors, while in turn it has beneath it the 
flexor perforans digitorum profundus. About halfway down the 
leg it gives way to a strong tendon, which, passing deep in the 
tibial cartilage, crosses the ankle-joint to pass through the outer 
canal of the osseous portion of the hypotarsus of the tarso-metatarsus. 
Down the back of the shaft of this latter bone the tendon exhibits a 
disposition to develop an osseous rod in its continuity, but this does 
not actually occur in my specimen. It lies in this region just above 
the tendon of the deep flexor, and, immediately above the sole, 
makes a fibrous connection with it of some extent, This fibrous 
“vinculum”’ is in no way oblique as it is described by Garrod for 
many birds, but passes directly from one tendon to the other for 
about 8 millimetres, and were it not known that it as a rule passes 
obliquely from the flewor longus hallucis, it would be quite impossible 
here to designate which tendon was responsible for the connection. 
In the foot the long tendon of the Aad/ux passes in the usual way 
to become inserted on the tubercle at the underside of the proximal 
end of the ungual phalanx, 
As its name indicates, our next muscle, the flexor perforatus 
indicis primus pedis (Plate XLV. fig. 1, f,), has its tendon attached 
to the nether side of the basal phalanx of the index digit, and 
consequently aids in bending that toe. 
Above, as a flat, long muscle, it comes off by a thin tendon from 
the external surface of the outer femoral condyle, arising with the 
flewor perforatus medius secundus pedis. 
We also have in Geococcyx an unusually large flexor perforatus 
medius primus pedis (Plate XLIV. fig. 2, f,), which here arises by 
two slips, an outer tendinous one, from the external condyle of the 
femur, which has a common origin with other muscles there arising 
and is intimately connected with the dense fascia about the front of 
the knee-joint ; while the second slip arises from between the femoral 
condyles, in common with other flexorsthat come off from that point. 
The two heads are quite independent, but merge with each other 
before they terminate in their common tendon at the lower third of 
the tibial shaft. 
It passes through the tibial cartilage, overlaid by, but in close 
company with, the far more diminutive and narrower tendon of the 
flexor perforatus annularis primus pedis. 
When it arrives under the basal phalanx of the median toe, the 
outer one of the anterior pair, it bifureates to allow the other two 
flexor tendons to pass, while the slips thus formed become attached 
to the sides of the shaft of this joint close to its distal head. 
32* 
