106 MEMOIRS OF THE CARNEGIE MUSEUM 
last sacral vertebra is entirely free from those in front of it and all of its diameters, 
though of considerable size, are much reduced, when compared with the heavy spines 
of the first two vertebrae. The postzygapophyses are quite well developed and bear 
distinct articular facets for the prezygapophyses of the first caudal vertebre. The 
posterior extension of the pleurapophyses exhibits a free area back of the iliac con- 
Fia@. 62. Lateral View of Sacrum of D. hol- Fic. 63. Anterior, Superior and Fia. 64. Superior 
landi Peterson. {% nat. size. (Carn. Mus. Cat. Inferior Views of Caudal fromabout and Lateral Views of 
Vert. Foss., No. 2126.) the Middle of the Tail of D. hol- Posterior Caudal of 
landi Peterson. nat. size. (Carn. D.hollandi Peterson. 
Mus. Cat. Vert. Foss., No. 2135.) % nat. size. (Carn. 
Mus. Cat. Vert. 
Foss., No. 1823.) 
tact which is fully as large if not larger than is the case in Arch«otheriwm ingens (see 
fig. 62). 
Caudal Vertebre.— The caudal vertebre of the type of Dinohyus are not present. 
From several isolated bones found scattered throughout the bone-bearing layer of - 
the quarry and also from a vertebra (No. 2135) found in the same horizon north of 
the Niobrara River, itis plain that the tail was of practically the same proportionate 
length as that of the Oligocene genus. Cuts of this bone and of one of the posterior 
bones of the tail found in quarry No. 1 are here given (figs. 63 and 64). 
Riss. 
The ribs on both sides (especially the ones in the anterior portion of the thoracic 
cavity) are well represented in the type of Dinohyus hollandi. The first rib is some- 
what sub-cylindrical proximally and broadens almost immediately below the head, 
while in Archxotherium ingens it continues rod-like to a greater distance distally and 
flares out more suddenly at the ventral end. In the anterior portion of the series 
