On the distal caudals, the lateral cavity has nearly or quite disappeared. All the caudal vertebræ are proportionally shorter than in Diplodocus, and their chevrons have no anterior projection, as in that genus.
Fig. 1. Fig. 2.
Figure 1.—Caudal vertebra of Barosaurus lentus, Marsh; side view.
Both figures are one-eighth natural size.
The remains on which the present description is based are from the Atlantosaurus beds of Dakota, about two hundred miles further north than this well-marked horizon has hitherto been recognized.
For important aid in securing the fossils above noticed, the thanks of the writer are due to Mr. J. B. Hatcher, Dr. C. E. Beecher, and Mr. G. L. Cannon, Jr. The type specimens will be more fully described and figured by the writer under the auspices of the U. S. Geological Survey.
New Haven, Conn., December 21, 1889.
Explanation of Plate 1.
Figure 1.—Left tibia of Ornithomimus velox, Marsh; a, front view; b, distal end; c, transverse section.
Figure 2.—Left metatarsals of same specimen; a, front view; b, proximal ends; c, transverse section; d, distal ends.
Figure 3.—Phalanges of second digit of same foot; front view. a. first phalange; b, second phalange; c, third, or terminal phalange.
Figure 4.—Left metacarpals of same species, perhaps of smaller individual; front view.
Figure 5.—Left tibia of young Ostrich (Struthio camelus, Linn.); a, front view; b, distal end. The separate calcaneum was first observed by the writer's assistant, Dr. G. Baur, who prepared the specimen.
Figure 6.—Left metatarsals of young turkey (Meleagris gallipavo, Linn.); a, front view; b, proximal ends.
a, astragalus; as, ascending process of astragalus; c, calcaneum; f, fibula; f', face for fibula; II, second metatarsal; III, third metatarsal; IV, fourth metatarsal.
Figures 1—4 are one-third natural size, and figures 5 and 6, one-half natural size.
