CONTENTS XV 



Figure Page 



438. Upper teeth of Menodus ■proutii 528 



439. Skull of Menodus trigonoceras 629 



440. Skull of Menodus trigonoceras belonging with the mounted skeleton in the Colorado Museum, Denver 530 



441. Restoration of Menodus giganteus 531 



442. Skull of Menodus giganteus, front view 532 



443. Skull of Menodus giganteus, palatal view 532 



444. Sections and contours of skulls of Menodus giganteus and M. various 534 



445. Sections and contours of skull of Menodus giganteus 535 



446. Lower jaws of Menodus giganteus 536 



447. Teeth and nasals of Menodus montanus i 538 



448. Sections and contours of nasals and horns of Megacerops coloradensis 544 



449. Sections and contours of skull of Megacerops bucco 545 



450. Sections and contours of skulls of Megacerops copei and M. acer 546 



451. Upper part of occiput of Megacerops acer 547 



452. Skull of Megacerops acer, side and top views 548 



453. Skull of Megacerops acer, palatal view 549 



454. Restoration of Megacerops copei 549 



455. Lower jaws of Megacerops assiniboiensis and M. riggsi 550 



456. Sections and contours of skull of Megacerops? syceras 550 



457. Composite sections showing the evolution of the horns and reduction of the free nasals in the Brontotherium phylum. _ 551 



458. Basal sections of the horns in the Brontotherium phylum 552 



459. Skulls of male and female brontotheres 552 



460. Contrast in contour of horns and nasals between male and female brontotheres 552 



461. Sections and contours of skulls of Brontotherium leidyi and B. hypoceras 558 



462. Lower jaws of Brontotherium leidyi ' 559 



463. Two lower molars and symphyseal region of Brontotherium? rumelicum 560 



464. Lower jaws of Brontotherium rumelicum? and B. leidyi 561 



465. Sections and contours of skull of Brontotherium? hatcheri 563 



466. Skull of Brontotherium hatcheri, side view j 564 



467. Skull of Brontotherium hatcheri, front view 564 



468. Lower jaws of Brontotherium hatcheri and B. gigas 566 



469. Sections and contours of skull of Brontotherium? tichoceras 567 



470. Sections and contours of skulls of Brontotherium hatcheri and B. gigas 568 



471. Lower jaws of Brontotherium gigas and B. medium 569 



472. Sections and contours of skull of Brontotherium gigas? 572 



473. Sections and contours of skull of Brontotherium dolichoceras 572 



474. Skull of Brontotherium dolichoceras 572 



475. Sections and contours of skulls of Brontotherium medium and B. curtum 674 



476. Horns of Brontotherium curtum 576 



477. Sections and contours of skull of Brontotherium curtum 576 



478. Left horn and nasals of Brontotherium curtum? 577 



479. Sections and contours of skull of Brontotherium ramosum 578 



480. Restoration of Brontotherium platyceras 579 



481. Sections and contours of skull of Brontotherium platyceras 580 



482. Evolution of the skeleton in titanotheres 584 



483. Estimated height at shoulder of Eocene and Oligocene titanotheres and tapir 585 



484. The phyla of Eocene titanotheres, as represented by the manus 587 



485. Progressive broadening of the magnum in Eocene titanotheres 587 



486. Reconstructed skeleton and restoration of Lambdotherium popoagicum 591 



487. Atlas and scapula of Lambdotherium popoagicum 591 



488. Fore limb of Lambdotherium popoagicum 592 



489. Forearm and manus of Lambdotherium popoagicum 592 



490. Left manus of Lambdotherium and Eotitanops 592 



491. Astragalus of Lambdotherium popoagicum 593 



492. Restorations of Lambdotherium popoagicum, Eotitanops princeps, and E. gregoryi 593 



493. Metatarsals of Eotitanops 593 



494. Reconstructed skeleton and restoration of Eotitanops borealis 594 



495. Atlas of Eotitanops borealis 595 



496. Vertebrae of Eotitanops princeps 595 



497. Radius of Eotitanops borealis 595 



498. Lunars of Eotitanops 595 



499. Manus of Eotitanops princeps 595 



500. Humerus and femur of Eotitanops princeps 596 



501. Pelvis of Eotitanops borealis -• 596 



502. Left pes of cursorial and subeursorial Eocene Perissodactyla 597 



503. Astragalus and calcaneum of cursorial and submediportal Eocene Perissodactyla 598 



504. Astragalocalcaneal facets in lower Eocene Perissodactyla , 598 



505. Left astragalus and calcaneum of Eotitanops sp 599 



