1882.] | DR. GADOW ON THE ANATOMY OF PTEROCLES. 317 
margin of the postacetabular ilium and from the lateral plane of the 
distal half of this bone. Its tendon passes through the tendinous 
loop near the poplitea, and is inserted into the neck of the fibula. 
Its nerves come from the ischiadic plexus. 
M. caude ilio-fleworius (m. semitendinosus). See fig. 1. This 
ribbon-shaped muscle arises from the lateral processes of some of the 
first caudal vertebre and from the outer plane of the spina ilio-cau- 
dalis. The so-called accessory part of this muscle is well developed ; 
it descends from the outer and lower surface of about the distal 
third of the femur ; and its fibres join those of the long or main part 
nearly at right angles. The line of junction is indicated by an 
oblique tendinous raphe. The two combined parts are inserted, 
first into the neck of the tibia by a strong tendon; secondly, a 
small tendon, looking like the continuation of the raphe, descends 
superficially to the back of the leg and joins the caput femorale 
internum m. gastrocnemii. Nerve-supply, together with the next 
muscle, from the ischiadic plexus. 
The m. ischio-flexorius (m. semimembranosus) is feebly developed, 
and loses its independence by becoming blended with the m. caudee 
ilio-flexorius, which completely covers it externally. It arises from 
a small part of the middle line of the lateral margin of the ischium. 
The m. caude ilio-femoralis consists of two chief parts. The 
most lateral one, or long head (long head of femoro-caudalis), is a 
very narrow, slender, muscular ribbon, which arises from the proce. 
lat. of the last caudal vertebree, and is inserted by a narrow thin 
tendon into the latero-posterior plane of the end of the proximal 
third of the femur. Towards its insertion the fleshy part of this 
long head is to a great extent blended with the more proximal or 
greater part: the latter (accessory femoro-caudal) arises from part 
of the membrane of the foramen oblongum, and from the outer 
plane of the hindmost or distal part of the ischium, whilst only a 
few fibres arise from the adjacent part of the ilium. The nerve 
which supplies these two muscles comes from the ischiadic plexus, 
and passes externally over the m. ischio-femoralis. I must mention 
here a peculiar little muscular slip which I have not often observed 
in birds. It arises (see fig. 1) as a small fleshy flat slip from the 
outer aspect of that region where the pubis and ischium approach 
each other; it is then partly covered by the long head; its thin 
tendon unites with that of the long head. It was present also on 
the other side, and was supplied by the same nerve-branch together 
with the two large heads. The presence of this little muscular slip 
is an instance of the great variation to which this group of the m. 
caudz ilio-femoralis is subject. 
The m. ischio-femoralis (m. obturator externus) arises with 
fleshy fibres from the dorsal, distal, and ventral margins of the foramen 
oblongum ; its strong tendon is inserted into the outer plane of the 
femur, just distad from the insertion of the m. obturator. It receives 
its nerve from the ischadic plexus. 
The m. obturator arises from that part of the inner plane of the 
ischium whieh bounds the foramen obturatum and also from the 
