60 
“‘ several small irregular gritty specks like imperfect sesamoids”’ in the 
tendon at the wrist* (cf. also Meckelt). 
In this animal, however, Coues found a small fusiform belly 
embedded in the substance of the muscle, and ending in a fine tendon, 
which was traced distinctly to the wrist, and then lost. This he took 
to be palmaris longus. He also found in the palm a small muscle, or 
rather four small muscles, arising from the palmar aspect of the tendon 
of the deep flexor. The fine tendons of these slips he found partly to 
join those of the deep flexor, and partly to be arranged like those of a 
flexor sublimis, to which accordingly he homologises it. 
Meckel refers to the last, but does not name it; and he states that 
the four small tendons are inserted, not into bone, but into the inter- 
digital membrane.$_ I think Coues’ view of the homology is probably 
correct, and if so the condition in Ornithorhynchus falls well in line 
with that described, ¢.g., in Cuscus, by Cunningham (supra p. 172), 
where the flexor sublimis was reduced to four small fleshy slips arising 
in the forearm from the surface of the deep flexor mass. There is, 
however, another possible view of the palmar fleshy slips in Ornitho- 
rhynchus, viz., that they represent a palmaris longus. The superficial 
position of the slips, and the somewhat indefinite ending of their 
tendons in sheathing the digital flexor tendons is at least equally ex- 
plicable upon such an hypothesis. There is certainly no other repre- 
sentative of the palmaris longus present. 
I have traced the small fusiform muscle which Coues found embedded 
in the flexor mass in Ornithorhynchns. Its fine tendon, surrounded by 
the musculo-tendinous fibres of the rest of the muscle, is attached to 
one of the sesamoid bones in the common tendon. It undoubtedly 
corresponds, not to the palmaris longus, as Coues thought, but to the 
‘“centralis” flexor eiement of Windle.|| It is indeed a fairly typical 
example of this factor of the flexor mass. 
Both in Echidna and Ornithorhynchus the great flexor muscle is ulnar 
and entocondylar in origin. 
In Chlamydophorus there is a palmar sesamoid ossicle, and to it three 
muscles are attached, according to Macalister. The first he regards 
as flexor sublimis, and is the only condylar part of the flexor mass. . It 
as attached to the ulnar side of the palmar sesamoid. I should think 
it highly probable that this in reality is only the condylar portion of 
the deep flexor, or at least of an only partially differentiated flexor 
mass. There are, at any rate, no insertion slips which correspond to 
those of a flexor sublimis. The other sectors of the flexor mass attached 
to the palmar ossicle are an ulnaris (Macalister’s flexor profundus) and 
a radialis (flexor longus pollicis). The three sectors seem to be quite 
separable in the forearm. From the distal end of the ovate ossicle five 
tendons proceed, including an exceedingly fine one to the pollex. 
But Macalister describes in addition** seven fine fleshy bundles 
arising from the sesamoid bone, which are inserted into each side of 
the second phalanges of the fingers except the thumb, and the ulnar side 
of the minimus, “ forming short fiexors.’”” These slips at once remind 
one of the very similar slips in Ornithorhynchus, and, as in that animal, 
See E Ma : a ae = ee Be 
* l., page 154. A XXXVil., page 28. F ul., page 155. S XXXV tra RAES 28, 
and xxxviil., page 559. || Ixvlii., page 74. {| xxvii., page 251. XXVil., 
page 252. 
