DR. GUNTHER ON THE ANATOMY OF HATTERIA. 
611 
separate plates, is worked as if it were but a single piece, like an abdominal plate of a 
snake, all the plates being firmly united to the underlying abdominal rib. 
4. When the fore part of the body is fixed, the action of the M. rectus (assisted by 
the pectoralis major) is to approximate the abdominal ribs and plates to one another, 
or to draw the hind part of the body forwards. 
5. The end of the hsemapophysis is fixed in the middle of each branch of the abdo- 
minal rib — that is, exactly at the point where the greatest effect on the rib can be pro- 
duced. 
6. The action of the pair of haemapophysial muscles is to draw the haem apophysis, 
and with it the abdominal rib, backwards ; the abdominal rib being attached to the base 
of the ventral plates, the edges of the latter must be raised, thus taking hold of any 
roughness of the ground with which they come in contact. The advantage derived 
therefrom, when the animal ascends a declivity, is evident. 
I do not for a moment entertain the idea that an individual of Hatteria with the limbs 
disabled could glide from the spot where it lies, nor am I convinced that the action of 
the abdominal apparatus is constantly superadded to that of the limbs ; but in the case 
of a lizard living on the rocks and sand-hills of the sea-shore the occasions must be 
frequent when the feebleness of its claws is complemented and assisted by its ventral 
plates. If the supposition should be confirmed that Hatteria lives in holes, where the 
free action of the limbs is naturally more or less impeded, the abdominal apparatus 
would be of material service. However, this habit has been attributed to it by Dief- 
fenbach only on the authority of natives, and it is not in accordance with the feeble 
development of the claws and with the presence of a much developed dorsal crest ; at 
all events it is obvious that the holes could not have been burrowed by the animal itself. 
Bones of the Fore Limb. 
The cartilaginous portions of the scapula and coracoid (figs. 25 & 26) are very broad, 
that of the former being larger than the ossified portion. The osseous scapula (g) is, 
as usual, constricted in the middle, and there is in the concavity of the anterior margin 
a very distinct acromial tuberosity (A), to which the clavicle is attached by a strong liga- 
ment. The coracoid has no notch whatever ; its osseous portion (e) is an irregularly 
subsemicircular disk, with a narrow foramen * (for the passage of blood-vessels) near the 
suture formed with the scapula, and with a second, less distinct, near its posterior 
extremity ; its cartilaginous border is narrowest in its posterior half, where it is received 
into the glenoid cavity of the sternum ; towards the front it widens to fill the angular 
space between episternum and clavicle. The glenoid cavity of the sternum is deep and 
long, like a slit, and the entire joint is formed by cartilage; the ligaments connecting 
these cartilages and fixing the coracoid to episternum and clavicle are strong, though 
very loose, allowing of great extent of motion. The humerus is very similar in form to 
that of Varanus, JJromastyx and others, being much expanded at its extremities, and 
* It is also very distinct in the Crocodile and Yaranus. 
4 o 
MDCCCLXVII. 
