PEOFESSOE OWEN ON THE SPECIES OF PHASC0L05ITS. 497 



narrow tract (fig. 9, 5) with the tibial malleolar surface (fig. 8, d), and below with the 

 surface articulating anteriorly with the cuboid and continued backward expanding 

 (fig. 9, a) to rest upon and articulate with the calcaneum. 



The calcaneum (PI. LXX. fig. 8, cl, and fig. 10) has three articular surfaces on its 

 expanded tarsal or articular half: — one above, feebly convex, subtriangular in shape 

 (fig. 10, a), for the astragalus ; one anterior, concave (5), for the cuboid ; and a narrow 

 slip continued therefrom to the inner side of the bone for articulation with the scaphoid. 

 The posterior fulcral or ' sesamoid' part of the bone (ib. ct) is triedral, broad, and 

 convex below, concave on the inner side (fig. 10, c), toward which the lever (ct) is 

 slightly bent, flat and rough on the outside : this part shows an oblong tuberosity (d) ; 

 and there is a second, smaller, hemispheroid one (e) close to the cuboidal articular 

 surface. 



Of the three cuneiforms the mid one (fig. 8, cm) is the smallest ; their relations to 

 the toes are shown in PI. LXX. fig. 8. That with the scaphoid is analogous to, or 

 homotypal with, the proximal relations of trapezium, trapezoides and magnum with 

 the scapho-limar in the carpus (PI. LXX. fig. 5, t, z, m). The cuboid (fig. 8, h), like the 

 unciform (fig. 5, m), is the largest of the distal series. It presents a convexity behind for 

 the astragalus and calcaneum, a small surface for the outer end of the naviculare, and 

 expands as it advances to support part of the proximal ends of the fourth and fifth meta- 

 tarsals, the latter sending outward an obtuse process beyond the proximal articulation. 



The 'pyramidale' (ib. fig. 8, 0) has a slightly convex non-articular base, which is 

 turned backward ; the three sides of the cone are almost flat and articular ; the under 

 anterior one plays upon the hinder part of the upper articular surface of the astragalus, 

 the upper one upon the hind end of the horizontal terminal articular surface of the tibia, 

 the outer one upon the hind end of the malleolar surface of the fibula. 



The metatarsals progressively increase in length and breadth from that of the hallux 

 (i) to the fourth (iv) ; that of the fifth (v) is somewhat shorter, but is twice as thick as 

 the fourth, and sends outward and backward a strong obtuse process fi-om its outer 

 and basal part. The hallux is reduced to one phalanx ; the other toes have the usual 

 number of phalanges, progressively increasing in thickness from the second to the outer- 

 most, but in a slighter degree in in. than in iv. and v., thus showing a slight tendency 

 towards the condition' described in the ' Cyclopsedia of Anatomy and Physiology,' 

 vol. iii. (1841), Art. Marsupialia, p. 286, fig. Ill, 



' Flower, ' Osteology of the Mammalia,' 12mo, 1870, p. 321. • 



