REPTILES ALLIED TO H A D R S A URU S. 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. MantelF as the clavicle of the Iguanodon, but appears 

 to me rather to resemble the pubic bone of the Iguana and Ci/dura 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 Iguanodon. 



To Hadrosaurus we may estimate the number of cervical, dorsal, and lumbar 

 vertebrae to have been twenty-four, as in the living Iguana and Cyclura, and as is 

 supposed to have been the case in Iguanodon. 



The sacrum was most probably composed as in the latter of six vertebrae. 



In attempting to ascertain how many vertebree 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 vertebrae to have been about fifty. 



By calculating the length of the vertebrae in different portions of the column, 

 making proper allowance for the intervertebral fibro-cartilages, and giving about 

 two feet and a half for the skuU, I would estimate the entire length of Hadrosaurus 

 to have been about twenty-five feet. 



The enormous disproportion between the fore and hind parts of the skeleton 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. 



Undetermined Reptiles allied to Hadrosauribs. 



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 XVII, is a left humerus, from Monmouth County, New 



* British Fossil Reptiles, Dinosauria, PL I, II. 

 ^ Petrif., &c., page 306, Fig. 65. 



13 April, 1865. 



