a4 
the very broad base of the ungual phalanx of the fourth digit, 
which is indeed fused with the base of the claw itself. 
In accordance with the peculiarly modified manus in Notoryctes, this 
muscle exhibits a marked reduction from the ordinary marsupial type. 
In Koala* Young describes an insertion into each of the five digits. 
This, Cunningham remarks,} is exceptional, as “in the great majority 
of marsupials its insertion is limited to the four inner digits.”’ 
[I do not think that Young’s interpretation of the extensor group of 
muscles in Koala is acorrect one. In several points it differs markedly 
from Macalister’s brief account. I have dissected a young specimen 
in order to decide certain differences. I find that the extensor com- 
munis digitorum arises from the ectocondyle, and divides above the 
dorsal carpal ligament into three tendons, one for the medius, another 
for the medius and annularis, and a third, which is very broad in the 
dorsum of the hand, mainly for the minimus, but partly also for the 
annularis. The fibres of the last two tendons thus undergo a partial 
decussation. The first-named tendon (for the medius) passes through 
a separate theca. No tendon goes to either index or pollex, but the 
proper media! tendon is connected by a strong and somewhat rounded 
trausverse vinculum with the indicator tendon. ] 
In Yhylacinus, according to Cunningham, the muscle is trifid in the 
forearm, each tendon subsequently splitting, the six tendons being 
distributed tc the four ulnar digits. 
In Echidna Mivartt~ describes the muscle as bicipital, one head 
being ulnar in origin. He only notes tendons of insertion into the 
three middle digiis, while Westling$ describes a tendon going to the 
terminal phalanx of each of the five digits. 
In Ornithorhynchus the muscle is not bicipital, and arises only from 
the ectocondyle, its terminal tendon expanding on the back of the 
hand, and sending a slip to the distal phalanx of each of the five digits 
(Brooks||). 
In Chlamydophorusi the muscle passes unbroken beneath the 
annular ligament, and then goes to be inserted into the second, third, 
and fourth digits. 
The precise insertion varies in Edentates ; in several cases it is into 
second, third, and fourth digits, as in Chlamydophorus, but it may be 
into second and third, third and fourth, or third only. 
In Erinaceus, which is so very slightly specialised, it is inserted into 
each of the five digits. 
In Chrysochloris** the insertion is into the third and fourth digits 
only. In this animal, it will be remembered, the manus is modified in 
somewhat similar manner as in Notoryctes. 
No MM. extensor minimi digiti (extensor secundus digitorum 
auct.,' is present. 
Such 2 muscle, designated by Macalister+}+ as “ extensor secundus 
digitorum,” is constantly present amongst other Marsupials, and is 
generally inserted into the fourth and “fifth” digits, rarely into the 
* Ixxii., page 229. tiv., page 15. +} xxxix., page 387. § Ixii., page 26, 
and fig. 14. ||i., page 8. {I xxvii., page 256. ** xxvi., page 813. tT xxix., 
page 164. 
