HADROSAURUS. 81 
The abutments of the vertebral arch present a slight successive increase in width. 
In the first specimen it is twenty lines wide; in the tenth specimen twenty-two 
lines. 
The articular processes are like those of the preceding caudal vertebra, and suc- 
cessively increase their distance apart Thus in the second specimen of the series 
under consideration the space reaching from those anterior to the ones posterior 
measures forty-six lines; in the third specimen the same space occupies forty-eight 
lines; and in the tenth, fifty lines. 
The spinous process, preserved entire in the third specimen (Fig. 13), is eight 
inches and a half long. Directed upward and backward it is at first cylindrical, 
but approaching its free extremity becomes laterally compressed. Judging from 
the remains of this process in the other caudal vertebre, it has had a similar form 
throughout. 
The transverse processes are apparently all broken or bruised at the ends in the 
vertebre in which they have existed. In the six specimens in advance they appear 
to have been formed as distinct elements, and were apparently coossified by a 
broadly expanded root to the conjunction of the vertebral body and arch. In the 
anterior two-specimens (Figs. 11, 12) they appear to have been short, robust promi- 
nences, with their root extending nearly as far down as the middle of the side of 
the body. In the succeeding three (Fig. 13) specimens the processes appear to 
have been short, obtuse prominences, not reaching by their expanded root below 
the upper third of the side of the body. In the next three of the series, as seen 
in Figs. 14, 15, the transverse processes are obsolete, or appear as a slight, rough- 
ened prominence, dt or below the union of the vertebral body and arch. In the 
last specimen no trace of the process appears, as seen in Fig. 16. 
The remaining five caudal vertebre of the collection, of which the back four 
are represented in Figs. 17-20, possess the same general form of the body as in the 
preceding specimens, and exhibit a successive diminution of depth and breadth in 
relation with the length, which also undergoes a moderate reduction. ‘Thus in the 
first of the specimens the body is nearly of equal length, depth, and width, their 
measurements being about three inches. The body of the succeeding three speci- 
mens (Figs. 17-19), which are nearly equal in size, is thirty-three lines long, twenty- 
eight wide, and twenty-five deep. The last specimen (Fig. 20) has its body thirty 
lines long, and twenty-one wide and deep. 
In the first of this series the spinal canal is vertically oval, eight lines high, and 
six wide; in the fourth specimen it is subcircular, five lines and a half wide and 
high. 
The abutments of the vertebral arch in the first specimen are twenty lines wide; 
in the fourth specimen, thirteen lines. 
Transverse processes appear not to have existed in these five caudal vertebra, as 
no trace of them is visible. The vertebral arch in all+is too much mutilated to 
ascertain whether it was provided with articular and transverse processes. 
All the vertebre I have described appear to be fully grown, their arch being 
firmly coossified with the body. ‘The sutural conjunction between the two arts 
ll April, 1865, 
