18 THE VOYAGE OF H.M.S. CHALLENGER. 



Pes. — The tarsus contained seven bones. The astragalus was the largest bone of 

 the foot, and articulated with the tibia by its superior surface, and with the fibula by its 

 external lateral surface, and its fibular surface was almost as large as the tibial ; also 

 with the os calcis by its inferior surface, which possessed two facets separated by a deep 

 groove for an interosseous ligament, and by its anterior surface or head with the scaphoid 

 bone ; it also had a posterior process which, though massive, did not projedt quite so 

 far back as the calcanear process of the os calcis, and was not grooved posteriorly. 

 The os calcis grooved for the peroneal tendons articulated with the astragalus and 

 cuboid ; its calcanear process was longer than, but not so massive as, the posterior process 

 of the astragalus, and possessed at its free end a separate epiphysis. The scaphoid had 

 the characteristic form of the bone and articulated with the astragalus, cuboid, and three 

 cuneiforms. Its tubercle for the tibialis posticus was massive, and it had also a pointed 

 plantar process. The cuboid had a plantar ridge and peroneal groove ; it articulated 

 with the 4th and 5th metatarsals, and by a very small surface with the 3rd, also with 

 the calcaneum, scaphoid, and ecto-cuneiform. The three cuneiforms varied much in 

 size, the ento- was the largest, the ecto- next in size, and the meso- so small as only to 

 be seen on the dorsum of the foot. The ento- articulated with the 1st and 2nd 

 metatarsals, the scaphoid, and meso-cuneiform. The meso- with the other cuneiforms, 

 the scaphoid, and the 2nd metatarsal. The ecto- with the 2nd and 3rd metatarsals, 

 the meso-euneiform, cuboid, and scaphoid. 



There were five toes. The hallux and minimus, notwithstanding the difference in the 

 number of segments, were of almost equal length, although the hallux had slightly the 

 advantage. The 2nd and 4th toes, almost of equal length, reached to about the level of 

 the articulation of the terminal and penultimate phalanges of the hallux. The 3rd toe was 

 the shortest and ended almost opposite the joint between the 2nd and 3rd phalanges 

 of the 2nd toe. The segments of the hallux were longer than the corresponding segments 

 in the other toes. The 2nd metatarsal was in close relation to the outer side of the 

 1st, and the tarsal end passed behind that of the 1st, so as to articulate with nearly one- 

 half of its proximal end, the remainder being for the internal cuneiform ; this arrange- 

 ment gave to the tarsal end of the 2nd metatarsal a hook-like form ; it articulated with 

 all three cuneiforms and with the 1st and 3rd metatarsals. The 3rd metatarsal was the 

 shortest and articulated at its proximal end with the ecto-cuneiform, slightly with the 

 cuboid, and with the 2nd and 4th metatarsals. The 4th metatarsal was in close apposi- 

 tion with the 5th, and its tarsal end was hollowed on the outer side to allow the 5th 

 metatarsal to be lodged in it ; it articulated with the 3rd and 5th metatarsals and the 

 cuboid. The 5th metatarsal, though shorter than that of the hallux, was if anything 

 more massive ; its tarsal end articulated with the 4th metatarsal and cuboid, and was 

 somewhat elongated into a process on the outer side of the foot. The ossification of the 

 metatarsals and phalanges was on the same plan as that of the metacarpals and phalanges 



