46 
pal, e.g., in Phascolarctos, Phalangista maculata, Thylacine (sometimes), 
Phascolomys, and Myrmecobius.* But where there are two tendons of 
insertion one may pass to the os hamatum, while the other goes to the 
fifth metacarpal, as in Phascogale and one specimen of Thylacinus 
(Cunningham), or as in Dasywirus and Sarcophilus,t both tendons pass 
to the metacarpal bone of the fifth digit. 
In Echidna Mivart{ notes the muscle as both ectocondylar and ulnar 
in origin, i.e.,from clecranon. Westling$ mentions also a fleshy origin 
from the ulnar shaft. The latter I have not been able to verify from 
dissections. Mivart merely gives as its insertion the outer side of the 
dorsum of the fifth digit, but Westling describes it as joining the 
extensor tendons of the fifth digit, and being inserted into the lateral 
borders of the middle and base of the terminal phalanx. Wenzel 
Gruber,|| on the strength of Mivart’s observations, holds that in 
Echidna the “ ulnaris externus” is simply an “ ulnaris digiti quinti.”’ 
In Ornithorhynchus Brooks found the origin ectocondylar only, and 
that the tendon of insertion passed along with that of the extensor 
minimi digiti, and divided at the wrist into two. Of these one was 
inserted, as Westling found the tendon inserted in Echidna. The 
other, deeper, was joined by a slip from the abductor minimi digiti, 
and was then inserted into the base of the proximal phalanx of the 
little finger. Here also, therefore, as Brooks remarks, the muscle is 
converted into an ulnaris quinti digiti. 
This description is remarkably different from that given by Coues,** 
who specially states that, while all other muscles lying on the forearm 
are more or less condylar in origin, this one ‘‘ arises wholly from the 
ulna.” Further, he states that it is inserted into the base of the fifth 
metacarpal, ‘ partaking somewhat of the general tendency to aponeu- 
rotic expansion that characterises all the tendons coming down on the 
back of the hand.” 
Brooks’ view is in agreement with Meckel’s. The latter,++ in men- 
tioning the muscles attached to the ectocondyle, and after noting the 
extensor communis digitorum, proceeds :—“ Sequitur hunc latus et 
crassus, ulnaris externus, phalangi prime digiti quinti insertus.”’ 
Coues has plainly taken for extensor (his “ flexor’’) carpi ulnaris 
what Meckel and Brooks describe as “ extensor indicis et pollicis,” 
while he has taken the true extensor carpi ulnaris for extensor minimi 
digiti, apparently entirely overlooking the real extensor minimi, which 
lies more deeply. This author’s description of the mode of ending of 
the extensor tendons is extremely vague and unsatisfactory. In par- 
ticular, I cannot understand his statement that the tendon of his 
“flexor” (“ extensor” of ordinary anatomists) carpi ulnaris is inserted 
into the fifth metacarpal. Asa matter of fact, the tendon of the muscle in 
question does not pass at all near to the fifth metacarpal, but, as Brooks 
describes it, passes beneath the posterior annular ligament in the same 
compartment with the tendon of the extensor communis digitorum, 
and on the back of the hand distributes slips to the dorsal expansions 
* Ixxli., page 229; iv., page 15; xxix., page 164; and xxvi., page 816. 
tiv., page 15; xxxvi., page 126; and xxx., page 19. + xxxix., page 387. 
§ lxii., page 27. ||lx., page 24. (i., page 9. **iii., page 154. “Tf xxxvil., 
page 27. 
