1884.] MR. G. E. DOBSON ON CAPROMYS MELANURUS. 245 



obliquely into the distal third of the plantar surface or the first 

 metatarsal bone on its inner side. 



Extensor hallucis lonyus is well developed, arising from the middle 

 third of the shaft of the fibula and from part of the interosseous 

 membrane, and is inserted into the terminal phalanx of the hallux. 



Peroneus longus, brevis, quartus, quinti digiti. — All these muscles 

 are well developed, the p. longus arising as usual most superficially 

 from the head of the fibula, the p. brevis under it by an extensive 

 origin external to the lower third of the fibula, while, under cover 

 of it and external to it, the p. quartus and p. quinti digiti ; all the 

 tendons pass behind the malleolus and are inserted as usual. 



Extensor digitorum brevis is small, arising from the os calcis on 

 the fibular side of the astragalus ; divides into two tendons, of which 

 the inner unites with the long extensor tendon of the second toe ; the 

 outer is inserted into the base of the second phalanx of the third toe. 



This muscle should, evidently, be considered a pedal part of the 

 same mass from which the peroneus quartus and peroneus quinti 

 digiti tendons are derived. 



Gastrocnemius is very large, having the usual origin and insertion. 



Plantaris arises from the external condyle in close union for some 

 distance with the gastrocnemius : its tendon passes over the os calcis 

 and enters the foot, where it becomes continuous with the plantar 

 fascia and gives part origin to the flexor digitorum brevis. 



Soleus has a fibular head only, arising from the head of the fibula. 



Flexor digitorum tibialis arises from the head of the fibula under 

 cover of the popliteus, and between the internal margin of that muscle 

 and the origin of the tibialis posticus, and from the shaft of the tibia, 

 under cover of the popliteus, as far down as the commencement of 

 its lower third ; forms a strong tendon which passes through a groove 

 on the internal malleolus, on the fibular side of the tibialis posticus 

 tendon, and, entering the foot, unites with the tibial side and 

 superficial surface of the flexor fibalaris, forming the tendon for the 

 hallux and contributing to that for the fifth toe. 



Tibialis posticus. — Smaller than the preceding, between which and 

 the flexor fibularis it arises from the head of the fibula and along the 

 upper half of the shaft of the tibia ; forms a moderately large tendon, 

 which, passing across the internal malleolus on the tibial side of the 

 tendon of the flexor tibialis, is inserted into the scaphoid bone. 



Flexor digitorum fibularis is of great size, arising from nearly the 

 whole fibula, from the interosseous membrane, and from the middle 

 third of the shaft of the tibia ; forms a strong tendon which unites 

 with that of the flexor tibialis, as described above \ and is distributed 

 mainly to the three middle toes. 



Flexor digitorum brevis is very large, arising in two masses, a 

 superficial and a deep : the former arises from the plantaris and 



1 The relations and connexions of the above-described three muscles conform 

 in ;ill respects to the Hystricine type, as explained in the writer's paper, "On 

 the Homologies of the Long Flexor Muscles of the Feet of Mammalia; with 

 Remarks on the Value of (heir leading Modifications in Classification, " Joum. 

 Anat. & Phys. xvii. p. 142. 



