6 MEMOIRS OF THE CARNEGIE MUSEUM 
City, Colorado. The horizon is in the Jurassic” and some 100 to 150 feet above 
the summit of the red Triassic? sandstones. It is I believe a decidedly lower hori- 
zon than the dinosaur beds near Morrison, Colo. ; Como, Little Medicine Bow and 
Sheep Creeks, Wyoming or Piedmont, South Dakota. 
Tn the diagram of the quarry shown in Fig. 2 the bottom line shows the limit to 
which the quarry had been worked by Professor Marsh while the area above this 
line is that worked by Mr. Utterback for the Carnegie Museum. 
DerscrRIPTION OF THE Type (No. 572) or HApLocanrHosaurus Priscus. 
The Vertebree. 
The Cervicals (Plate I., Figs. C15 and 14).— Only the last two cervicals were re- 
covered. Fortunately these, together with the first dorsal, were still interlocked by 
their zygapophyses and thus the actual position of these three vertebree in the ver- 
tebral column can be definitely determined. They were somewhat crushed and 
distorted, but considering the hard and fractured nature of the sandstone in which 
they were imbedded they are in a very good state of preservation and remarkably 
complete. These vertebree are rather low, broad and short for the posterior cervi- 
cals of a Sauropod dinosaur of such dimensions as is indicated by the remains of 
the present skeleton and suggest a reptile with a neck which, though, of moderate 
length, was decidedly more abbreviated than was that of Diplodocus, a contempora- 
neous but more highly specialized Sauropod. 
The Fourteenth? Cervical (Plate I., Fig. C 14).— Assuming that there were the 
same number of vertebree in the cervical series of Haplocanthosaurus as in Diplo- 
docus, the first of the series of vertebree now under consideration would correspond 
to the fourteenth cervical. It is not improbable, however, that the number of cer- 
vicals in the present genus was less than in Diplodocus. Hence, I have interrogated 
the numerical position of this vertebra in the cervical series, although as already 
stated, there can be no doubt of its being the last but one of that series. 
The centrum is strongly opisthoccelous and with the transverse diameter exceed- 
ing the vertical, though these dimensions have doubtless been somewhat altered by 
pressure. The sides of the centrum are invaded by long and deep pleurocentral 
cavities® separated only by a thin median septum. These cavities are extended for- 
ward into the base of the ball of the centrum while posteriorly they are only sepa- 
rated by a thin plate of bone from the cavity for the ball of the succeeding vertebra. 
* By some considered as Lower Cretaceous. 
*For an explanation of the names applied to the various cavities, Jamine, etc. of the Sauropod ver- 
tebrze, see the author’s paper on Diplodocus, Mem. Car. Mus., Vol. I., No. 1, pp. 16-19. 
