18 A Review of the Muscles used 
springs from a longitudinal line occupying the distal half 
of the shaft of the femur, and from the upper surface of 
the hinder aspect of the external condyle of that bone. 
The fibres pass backwards and a little upwards to become 
inserted into the tendinous raphe just alluded’ to. The 
lower extremity of this tendinous raphe terminates, in G'eo- 
coccyx, in a thin, flat, and delicate tendon, which continues 
downwards and forwards to the inner surface of the head 
of the tibia, where it becomes inserted. the point of inser- . 
tion being found above that of the semimembranosus mius- 
cle, the insertional tendon of which overlaps it. 
As in the case with the other muscles described in the 
foregoing paragraphs, ornithotomists have a fine field open 
before them in dissecting out this group of thigh muscles in 
our United States birds; making full notes upon their re- 
searches, and comparing carefully with the work already 
accomplished by the indefatigable Garrod. In doing this, 
not merely the absence or presence of the five muscles last 
described should be noted, but if possible, full notes made as 
to their exact origins and insertions, their relative size as 
compar ed with other allied birds, and in short their morpho!l- 
ogy in its details. 
THE AREA OF THE ORIGIN OF THE OBTURATOR INTERNUS. 
In birds this muscle arises,as shown in the figure, from the 
central surface of the pelvis, its fibres being attached to the 
post-pubic bone and the ischium. As a rule it is a bipenni- 
form muscle, its fibres being directed forwards, but at the 
same time, on either side of its own moiety, towards-a long- 
itudinal tendinous and mid-line of its own. This tendon 
becomes stronger as it-approaches the obturator foramen, 
and passing through this, is finally inserted into the head 
of the femur of the corresponding side, and upon its outer 
surface. ! 
Now ina great many birds the area from which the obtura- 
tor internus arises is of an oval outline, while on the other 
hand in nearly an equalnumber of the class, this area will 
be found to bea trzangular figure. So it has been said, that 
it can thus be utilized as a good character, in this way, 
