J. Playfair McMurrich 423 
insertion. These last two muscles, Cunningham, 82, describes as a two- 
headed abductor quinti digiti. AJl three muscles are supplied by branches 
from the lateral plantar nerve. 
Ruge, 78a, describes the same three muscles, but Coues, 72, failed to 
find the abductor ossis metatarsi, the arrangement described by him being 
similar to that observed by Ruge in Didelphys cancrivorus. Further- 
more, Coues terms the oblique head of the abductor the flexor brevis 
minimi digiti, an objectionable term for it on account of its leading to a 
confusion both with the slip which passes to the minimus from the main 
mass of the flexor brevis superficialis and with the homologue of the 
muscle known by the same name in human anatomy (see p. 430). While 
Cunningham’s terminology for the muscles is acceptable, it may be noted 
that here, as in the case of the abductor hallucis, he is in error in referring 
them to his dorsal layer. 
In the lists which Cunningham, 82, gives of the muscles of his dorsal 
layer as they occur in the large number of mammals he studied, it will be 
noticed that while the three muscles occur in several marsupials, in other 
forms they are reduced to two and in others to one. When two exist they 
are a single-headed abductor and an abductor ossis metatarsi; and when 
but one occurs it may be either an abductor or an abductor ossis metatarsi. 
The cat belongs to that group of forms in which there are two muscles, 
an abductor ossis metatarsi (the caleaneo-metatarsalis of Reighard and 
Jennings, or), passing from the side of the tuberosity of the calcaneus 
to the base of the fifth metatarsal, and an abductor (the abductor medius 
quinti digiti of Reighard and Jennings), arising from the plantar 
aponeurosis over the abductor ossis metatarsi and inserting into the 
lateral metatarso-phalangeal sesamoid bone. 'The mouse, on the other 
hand, possesses only an abductor ossis metatarsi. The muscles of both 
forms are supplied by branches from the lateral plantar nerve. 
The flexor brevis superficialis stratum profundum is represented in all 
the mammalia studied by muscle fibers which are distinctly separated 
from those of the stratum superficiale and take their origin from the 
plantar surface of the long flexor tendon shortly before it divides into its 
slips for the digits. In the opossum the muscle forms a practically con- 
tinuous sheet, covering the entire width of the tendon, and divides dis- 
tally into four slips (Figs. 5 and 6, fbsp), one of which passes to each 
of the tendons of the main mass of the stratum superficiale. In the cat 
(Fig. 7, fbs,) and mouse the stratum is represented by only two slips 
which unite with the superficial tendons for the third and fourth digits. 
Those occurring in the cat have been described by Reighard and Jen- 
99 
Bes) 
