(C M ih ns OF LE Dy IN EG LE: )y hi 
18 MEMOIRS OF THE CARNEGIE MUSEUM 
The more important dimensions of the sacrum of the type of Haplocanthosaurus 
priscus are as follows: 
mm. 
Total length of the five coossified sacrals.......2....-..ceccsecrscereccerecsaceeesceene. 795 
Greatest expanse of transverse processes of first sacral....................0.00005- 640 
ce ee Wg Bg Va Sb poe erin caicoa emcee sence cen 700 
Height of top of neural spine above bottom of centrum in first sacral......... 520 
x ee oe a oe ue “s TAS Ui Mey lentes 485 
Anteroposterior length of three codssified neural spines .......... ...........-.-- 398 
Height of anterior neural spine above zygapophyses...................20e0e0s eee 252 
i posterior ‘‘ rit ef Ee vinta ataaneuenncrnenctactonendice 180 
The Caudal Vertebre (Plate III.).—Nineteen anterior caudals were found associated 
with the present skeleton. Their position in the quarry relative to one another and 
to the sacrum are shown in Figs. 1 and 2. 
The centra throughout the entire series of nineteen caudals are remarkably short 
when compared with the same vertebree in Diplodocus. They are somewhat con- 
stricted medially and are slightly amphiccelous with the concavity of the anterior ex- 
tremity more pronounced than that of the posterior. The centrum of the first caudal 
is the shortest of the series. From this they very gradually and slowly increase in 
length until the twelfth caudal is reached when they begin very gradually to de- 
crease in length. 
The neural spines throughout are comparatively short and directed somewhat 
backward. They are compressed and with rugose extremities which are quite simple 
throughout instead of being laterally expanded and emarginate as in caudals one to 
eight in Diplodocus carnegi. 
The anterior zygapophyses are slender and extended far forward in advance of 
the anterior extremities of their respective centra. The posterior zygapophyses are 
not extended beyond the posterior extremities of the centra. 
The transverse processes even in the anterior caudals are quite simple when com- 
pared with the same elements in Diplodocus and Brontosaurus. In the anterior 
caudals they appear as simple, broad plates of bone springing directly from the 
neural arches and the superior lateral surfaces of the centra. These bony plates are 
nearly flat and thin. They are entire instead of being perforated as in Dzplodocus, 
and their posterior and anterior surfaces are entirely destitute of that series of vertical 
or radiating laminee seen in the anterior caudals of Diplodocus carnegu. The trans- 
verse processes of the caudals decrease rapidly in size as we proceed posteriorly and 
in the twelfth caudal they are reduced to a rounded knob of bone on either side of 
the centrum near the superior border, while just above this on the middle of the side 
