REPTILES ALLIED TO HADROSAURUS. 97 
Another bone, the character of which I have not satisfactorily determined, is 
represented in Fig. 13, Plate VIII. It bears a general resemblance to that indi- 
cated by Prof. Owen' and Dr. Mantell’ as the clavicle of the Jguanodon, but appears 
to me rather to resemble the pubic bone of the Jywana and Cyclura than the clavicle 
of the same animals. 
The specimen, broken at its upper extremity, consists of a long and nearly 
straight cylindroid shaft, expanding at its lower extremity into a broad, thin, and 
flattened triangular plate. The borders of the latter are concave, and its outer 
and inner angles below form thick tuberous processes. A smaller process likewise 
projects from the outer part of the shaft just before it expands. The length of the 
specimen in its present state is twenty-six inches, the circumference of its shaft five 
inches, and the breadth of its lower extremity ten inches and a half. © 
A specimen of what appears to be a sesamoid bone is tetrahedral, with two 
concave surfaces separated by a prominent acute ridge and defined by rugged 
borders, and with two opposed surfaces, of which one is convex and the other 
nearly flat. The three axes of the bone measure forty-three, forty-one, and twenty- 
four lines. 
As regards the size, general form and construction, and the habits of Hadrosaurus, 
from the anatomical characters of the bones and teeth, we may safely infer that it 
bore a very near relationship with /gwanodon. 
To Hadrosaurus we may estimate the number of cervical, dorsal, and lumbar 
vertebree to have been twenty-four, as in the living /yuana and Cyclura, and as is 
supposed to have been the case in Jgywanodon. 
The sacrum was most probably composed as in the latter of six’ vertebre. 
In attempting to ascertain how many vertebra would be required, in the intervals 
of those caudals in our possession, to complete the tail of Hadrosaurus, I have sup- 
posed the whole number of caudal vertebre to have been about fifty. 
By calculating the length of the vertebre in different portions of the column, 
making proper allowance for the intervertebral fibro-cartilages, and giving about 
two feet and a half for the skull, I would estimate the entire feneth of Hadrosaurus 
to have been about twenty-five feet. 
The enormous disproportion between the fore and hind parts of the suclctdn of 
Hadrosaurus has led me to suspect that this great herbivorous Lizard sustained 
itself in a semi-erect position on the huge hinder extremities and tail while it 
browsed on plants growing upon the shores of the ocean in which it lived. 
Indetermined Reptiles allied to Hadrosaurus. 
In a number of instances bones, and fragments of others, have been presented to 
the Academy of Natural Sciences, approaching in size those of Hadrosaurus, though 
not positively referable to the same great Saurian. One of these specimens, repre- 
sented in Figs. 1, 2, 3, Plate X VII, is a left humerus, from Monmouth County, New 
4 British Fossil Reptiles, Dinosauria, Pl. I, II. 
* Petrif., &c., page 306, Fig. 65. 
13. «~April, 1865. 
