J. Playfair McMurrich 429 
are separated from the central portion by a tendinous partition. The 
entire mass eventually separates into two portions which insert 
respectively into the tibial and fibular metatarso-phalangeal sesamoids 
of the digit and seem to represent the two flexores breves profundi III 
together with the-intermetatarsales Il and III. In the fourth digit 
also there is much fusion of slips. A relatively large bundle passes 
from the fifth metatarsal to the fibular sesamoid of the digit, repre- 
senting the fourth intermetatarsal, but whether it also includes a por- 
tion of the flexor profundus IV remains uncertain. The main mass 
of the flexor profundus V passes to the fibular sesamoid of its digit, 
but it gives off a slp which unites with the adductor slip for the digit 
and appears to represent the tibial portion of the flexor profundus V. 
In the cat, owing to the reduction of the haliux, no representatives 
of the flexor brevis profundus I nor of the intermetatarsalis I exist. 
Otherwise the arrangement resembles closely that of the mouse. In the 
second digit only the two slips of the flexor brevis profundus (Fig. 7, 
fbp*), occur, and these pass to the two metatarso-phalangeal sesamoids 
of the digit. Both slips of the flexor profundus V are well developed. 
A comparison of the mammalian plantar muscles as described above 
with those of the lacertilia may be made as follows: 
Lacertilia. Mammalia. 
3 AN Flexor brevis superficialis str. super- 
Flexor brevis superficialis str. super- fisiate 
ficiale. Abductor hallucis. 
Abductor ossis metatarsi V. 
Abductor V. Abductor V, 
Flexor brevis superficialis str. pro- Flexor brevis superficialis str. pro- 
fundum., fundum. 
Lumbricales. 
Flexor brevis medius str. superficiale. + Hallucal slip of flexor brevis medius 
str. superficiale. 
Flexor brevis medius str. profundum. /dductors. 
Flexor brevis profundus intermeta- : 
Interossei. 
tarsales. 
IV. THE PLANTAR MUSCLES IN MAN. 
It remains now to consider the plantar muscles of the human foot in 
the light of the conclusions reached in the preceding pages, and in 
doing so the nomenclature employed in human anatomy may be fol- 
lowed. 
