Charles R. Bardeen 347 
the muscle has made tendinous attachments which correspond with those 
of the adult and the chief nerve branches have extended for a considerable 
distance into the muscle. 
In the adult muscle as a rule several small branches extend into the 
upper extremity of the muscle and one or two large branches enter the 
middle third of the muscle. Within the muscle these branches run in 
intramuscular septa and are distributed chiefly across the middle third 
of the component muscle bundles. These run obliquely from their origin 
from the tibia and surrounding aponeurotic sheets to the tendon of inser- 
tion which arises high in the muscle. 
The anterior tibial muscle is probably represented in the urodeles by the 
femoro-tibial muscle which extends from the lateral epicondyle of the femur 
to the tibia and os tarsale tibiale and is more or less fused with the femoro- 
digital or long extensor muscle. In reptiles and mammals the anterior tibial 
is fairly constant in general relations. It arises in most mammals from 
the proximal end of the tibia and is inserted into the lateral side of the 
tarsus or into the first metatarsal. In many mammals, including monkeys 
and apes, the muscle is partially divided into two portions from one of which 
a tendon goes to the metatarsal of the big toe (abductor hallucis longus), 
the other to the first cuneiform. This division may affect merely the tendon 
of insertion or extend into the belly of the muscle. In man there is not in- 
frequently (25% of bodies, Le Double) a similar division of the terminal 
tendon but this rarely extends to the belly of the muscle. Schomburg, oo, 
describes a distinct division of the anlage of the tibialis anterior in the 
embryo into two parts, that toward the tibial side representing an abductor 
hallucis longus. This division does not appear in the embryos I have 
examined. 
Extensor digitorum longus.—From the central portion of the dorsal 
myogenous sheet the extensor digitorum longus and the extensor hailucis 
longus are differentiated simultaneously (Plate IX, Fig. 1). The ex- 
tensor digitorum occupies a position relatively more fibularwards 
than in the adult. It is broad and ends below in a broad flattened process, 
or tendon plate, at the center of the dorsum of the foot. There is no 
very distinct division into special tendons. Two nerve branches extend 
to the deep surface of the muscle where this overlies the n. peroneus 
profundus. Schomburg, oo, has described conditions in a six weeks 
embryo which do not differ very essentially from those here given. 
In an embryo of 20 mm. (Plate IX, Fig. 2) we find that tendinous 
attachments have extended to the digits from the tendon plate and that 
proximally the muscle has extended more toward the tibia. The nerve 
supply corresponds with that of the adult. 
In the adult as a rule two chief nerve branches arise from the n. 
