J. Playfair MeMurrich 415 
has a considerable origin from the dorsal surface of the plantaris tendon 
as well as from the tarsus, passes to the second and third digits; while 
the fibular portion, which is strong, as it approaches the fourth meta- 
tarso-phalangeal joint, invests the fourth plantaris tendon and comes 
into such intimate connection with the fibular slip of the flexor brevis 
superficialis str. profundum as to be unseparable from it. 
This layer seems to correspond to Gadow’s, 82, second plantar layer 
(less the slips 7 and ¢ already referred to the flexor brevis superficialis 
str. profundum) together with slip a of his third layer. His second 
layer contains no slip to the hallux, while his third layer possesses two 
slips to that digit, one of which presents an appearance and arrangement 
similar to the hallucal slip of the flexor brevis medius str. superficiale 
of Scincus and Iguana. The same slip is described by Hoffmann, go, 
as the tarso-digitalis primus and by Perrin, 93, as No. 30 flexor of the 
first phalanx. The latter autnor.describes the middle slip as 91, tarso- 
flexor of the digits, and the fibular slip as the external portion of 
18, flexor of the fourth phalanx, the internal portion of that muscle 
being the slip of the flexor brevis superficialis str. profundum to the 
fourth digit. 
The flexor brevis medius stratum profundum (Figs. 3 and 4, fbmp) 
is a thin sheet which hes immediately dorsal to the str. superficiale and 
is separated from the flexores breves profundi by the deep branches of 
the plantar nerves. It arises from the bases of the fifth and fourth 
metatarsals and, to a certain extent, from that of the third, and its 
fibers are directed obliquely distally and tibially. It divides over the 
shafts of the metatarsals into four slips which pass to the fibular side 
of the metatarso-phalangeal fibro-cartilage of the first, second, third, 
and fourth digits. This muscle corresponds to the third plantar layer 
of Gadow, 82, with the omission of slip a, and to the deductors of Perrin, 
93. 
The flexores breves profundi (Figs. 3 and 4, fbp). These muscles 
form a layer resting directly upon the metatarsals and separated from 
the flexor brevis str. profundum by the deep branches of the plantar 
nerves. They form in Scincus ten slips, which do not, however, corre- 
spond by pairs to the five digits. So far as the three tibial digits are 
concerned a paired arrangement is clear, although the muscles for each 
digit arise from the next adjacent metatarsal. The fourth digit, how- 
ever, has three slips attached to it, and the fifth only one, an arrange- 
ment which may indicate a transference of one of a pair corresponding 
to the fifth digit to the fourth. 
