8 H. ST. J. BROOKS ON THE 
digitorum consists of four fleshy slips, which arise from the tarsus and from the 
dorsum of the metatarsal bones. The first slip passes through the interval between 
the tibial and intermediate sectors of the superficial stratum, and is inserted into 
the phalanges of the index digit. The second and third slips pass between the 
divisions of the intermediate sector and proceed to the third and fourth digits. 
The fourth slip makes its way between the intermediate and fibular sectors, and is 
inserted into the fifth digit. 
The peroneal nerve passes forwards from the back of the thigh, and winds 
round the neck of the fibula to pass under cover of the fibular sector. It runs 
almost vertically down the leg under cover of the superficial stratum of muscles, 
supplies both the superficial and deep stratum, and ends in cutaneous branches to 
the digits. 
Mrvart does not notice the continuation of the muscles on the extensor aspect 
of the proximal segment into the intermediate and tibial sectors and the middle 
segment ; and he describes the extensor ossis metatarsi hallucis (under the name of 
extensor hallucis) as the only representative of the extensor brevis digitorum.” 
In this description the following points are noteworthy :— 
1. The great development of the anconeus, which is here represented by 
the whole ulnar sector in the fore-limb, and whose insertion corres- 
ponds in extent to that of the supinator longus on the radial side. 
2. The almost equally slight differentiation of the radial sector, from which 
the ext. carpi radialis is not separated off. 
3. The more distal origin than in Hatteria of the deep layer of muscles, and 
the absence of any separate metacarpal heads. 
4. The important distribution of the nerve to the anconeus. 
5. In the lower limb, the imperfect separation of the superficial stratum 
from the quadricips extensor, and its origin to a greater extent than 
in Hatteria from the lower end of the femur. 
6. The insertion of the tibial and fibular sectors chiefly into the bones of 
_ the middle segment, and their consequent great resemblance to the 
radial and ulnar sectors in the fore limb. 
Ormthorhynchus. 
In the fore limb the imtermediate sector is represented by a well-developed 
ext. commums digitorum, which arises from the external condyle of the humerus 
between the ext. carpi ulnaris and ext. carpi radialis brevior, and is separate from 
these muscles almost up to its origin. It passes into a tendon which becomes broad 
and flat on the dorsum of the hand, and then divides into five tendons inserted into 
the terminal phalanges of the digits. The tendon to the thumb is weaker than the 
* Op. cit., p. 466. 
