724 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



posterior tip of the fibula in extreme flexion of the 

 foot; the outer smaller pit is for the "ligamentum 

 tarsi fibul are breve" (Schmaltz), which passes to the 

 outer side of the calcaneum. The lower fourth of the 

 shaft of the calcaneum above the cuboid facet is 

 externally roughened, apparently for the "ligamentum 



Lambdotheriijm, popoa/jicum EolUanons pri/iceps EotiUmops oreaorvi 



Figure 661. — Restorations of nine species of titanotheres from the 



lower, middle, and upper Eocene and lower Oligocene 



Drawn by Mrs. E. M. Fulda. About one-flftieth natural size 



tarsi fibulare longum" and perhaps also for the ex- 

 tensor brevis digitorum. The external keel of the 

 astragalar trochlea bears externally an articular band 

 for the fibula. Partly surrounded by this band and 

 lying behind it is a deep pit for the "ligamentum 

 tarsi fibulare breve." 



On the inner side of the astragalus the posterosu- 

 perior corner bears a large process for the "ligamentum 

 tarsi fibulare breve." The same ligament was probably 

 continued into the pit which lies below and in front of 

 the last-named process. Also on the inner side of the 

 astragalus near the lower end, above the navicular 

 facet, is a high prominence, apparently for the 

 ligamentum tarsi tibiale longum. Immediately 

 above this prominence passed the tendon of the 

 tibialis on its way to insertion on the proximal 

 end of the second metatarsal. 



The roughened anterior faces of the navicular, 

 cuneiforms, and cuboid doubtless betoken the 

 ligaments connecting these bones with the as- 

 tragalus and tibia. The roughened protuberance 

 on the back of the cuboid served not only for 

 the insertion of the ligamentum tarsi plantare 

 longum as stated above but also for the origin 

 of the interossei muscles on the sole. The large 

 prominence on the back of the entocuneiform 

 gave origin to the first interosseus. The front 

 faces of the three metatarsals were probably 

 overlain by the several bellies of the extensor 

 brevis digitorum, which in the tapir passes down 

 from the front of the calcaneum, from the ankle 

 ligament and bones beneath, to the proximal 

 phalanx of the middle toe, lateral slips being 

 given off to the proximal phalanges of digits II 

 and IV. 



The proximal end of Mts II is roughened 

 on its medial face for the tendon of the tibialis 

 anticus and probably for the "ligamentum tarsi 

 tibiale longum." The outer surface of Mts IV 

 is roughened near the proximal end, probably 

 for a branch of the plantaris ligament. 



The shafts of the metatarsals on each side in the 

 proximal third are roughened for the interossei 

 and adductors, which as in Tapirus may have 

 consisted of three pairs. (Murie, 1872.1, p. 166.) 

 The sides of the proximal phalanges, as in the 

 manus, are roughened proximally for the interos- 

 sei and probably to the lumbricales. The latero- 

 distal pits are for collateral ligaments, the dorsal 

 face, proximal end, for the extensor brevis 

 digitorum. On the plantar side the proximal 

 phalanges were overlain by the perforated ten- 

 dons of the plantaris, which were inserted into 

 the sides of the second phalanges. 



In the ungual phalanges the dorsal face, proxi- 

 mal portion, gave insertion to the extensor longus 

 digitorum; the plantar face gave insertion to the flexor 

 communis digitorum (flexor perforans). 



The lumbricales, which in Tapirus are very fully 

 developed, were attached to the sides of the flexor 

 tendons and were inserted on the proximal sides of 

 the first row of phalanges. 



