Charles R. Bardeen 303 
obturator nerve, but it seems not improbable that this represents the 
anlage of that portion of the pectineus which is supplied by the obturator 
nerve in many individuals. 
In an embryo of 20 mm. (Plate VI, Fig. 2), the pectineus occupies a 
position which corresponds with that of the adult muscle. The femoral 
nerve gives to it a large branch which passes at first across its outer 
surface about midway between its tendons of origin and insertion. I 
have been unable to trace a branch to it from the obturator nerve. 
In the adult, as is well known, the nerve supply of the pectineus is usually 
through a branch from the femoral but not infrequently also from the obtura- 
tor or the accessory obturator nerve. Paterson (91, 95) has shown that 
in man the muscle is often divisible into a superficial portion supplied by the 
femoral nerve and a deep portion supplied by the obturator nerve. Similar 
conditions are normal in some of the lower mammals, while in others the 
muscle may be supplied by the femoral nerve only or the obturator nerve 
only. The dorsal or femoral portion is probably derived from an anlage 
intimately associated with the iliopsoas anlage, the ventral portion from 
the anlage of the obturator externus. W. Leche has shown that in many 
mammals there is separated from the obturator externus a muscle which he 
calls the obturator intermedius and that in those forms in which the pectineus 
is supplied by the obturator nerve it is probable that this obturator inter- 
medius has entered into the formation of the anlage of the pectineus. 
The pectineus of the mammals is, together with the iliopsoas, probably 
represented in the urodeles and reptiles by the pubo-ischio-femoralis internus. 
This, like the pectineus, may be supplied wholly by the femoral, or in part 
also by branches from the obturator. The accessory obturator nerve, which 
in about 10% of bodies innervates, or helps to innervate, the pectineus muscle 
in man, indicates, perhaps, that the division of the limb musculature in man 
into dorsal and ventral portions is not strictly to be traced in the respective 
territories of the femoral and obturator nerves. Nerve elements belonging 
to the ventral territory may be normally bound up in the femoral nerve in 
those branches which supply the pectineus muscle. When those branches 
become isolated we have the accessory obturator nerve (see Hisler, g2). 
There is considerable variation in the extent of separation of the pectineus 
into two portions in the human body. The muscle is very frequently fused 
with the adductor longus. Occasionally a fasciculus passes from the iliacus 
to the pectineus or between the pectineus and the obturator externus. 
Sartorius——The sartorius develops from an anlage not directly fused 
with that of the quadriceps. Grifenberg has described a fusion near the 
ilium of the proximal ends of the aniages of the rectus muscle and the 
sartorius with that of the iliacus. In those embryos I have studied in 
which these anlages are beginning to appear the quadriceps anlage is 
quite distinct from that of both the sartorius and iliacus. The upper 
limit of the sartorius anlage approaches closely, however, the iliacus 
