610 
DR. GUNTHER ON THE ANATOMY OE HATTERIA. 
the aponeurotic borders of the MM. pectoralis major and obliqui externi , the latter being 
situated entirely on the sides of the trunk. The fibrous tissue is so strong, that the 
cutis can only be removed with the knife ; and it adheres not less firmly to the outer 
surface of the abdominal ribs ; the portions stretched from one rib to another are, 
although firm, very pliable, allowing of an easy approximation of the ribs. Immediately 
below this fibrous layer is the M. rectus ( d ), in the superficial substance of which the 
abdominal ribs are imbedded, and which transversely extends from one extremity of an 
abdominal rib to the other. Below the M. rectus is the fascia abdominalis (f), covered 
by the black peritoneum, and passing laterally into a very thin M. transversus abdominis. 
The dilated hsemapophyses with their special muscles lie between the M. rectus and the 
fascia abdominalis. Finally, it must be mentioned that the extremities of the fifteen 
anterior abdominal ribs are attached to the hinder portion of the pect oralis major. 
Abdominal ribs are developed in many Saurians and in a great number of Teleosteous 
Fishes; they may serve merely to strengthen the abdominal muscle and to afford a 
firmer and larger base for the attachment of muscular fibres, forming, as for instance in 
Saurians living on the ground, a kind of abdominal sole. When in continuity with the 
ribs proper (as in the Chameleon), they will essentially contribute to the support of the 
contents of the abdominal cavity, especially when these are pressed backwards by much 
inflated lungs, or when their weight is much increased by the addition of developed ova*. 
But in no Saurian, so far as we know at present, have they any relation to the external 
integuments ; this we find to be the case in many Clupeoids, where their dilated centre 
protects the sharp abdominal edge. 
As regards Hatteria , their increased number (exactly corresponding to that of cross 
series of external ventral plates) and their peculiar connexion with hsemapophyses 
dilated into a broad base for the attachment of muscles show plainly enough that this 
apparatus is subservient to some special function, viz. to assist in locomotion. 
I have arrived at this conclusion from the following considerations: — 
1. Hatteria lives on the ground, in rocky parts of the sea-shore, in sandhill-holes 
made by some other animal ; its limbs, although muscular, are, compared with the majo- 
rity of ground-lizards, short, especially the hind limbs. Its claws are comparatively very 
feeble, and acutely pointedf , showing that in a normal state they cannot be much used 
in dragging the heavy body, or even in burrowing. 
2. The series of external ventral plates are not less imbricate than their homologues 
in Ophidians ; they are covered with a very firm epidermis, much worn on the posterior 
edges. 
3. Each transverse series of ventral plates, although consisting of fifteen or sixteen 
* In the latter case they perform a service analogous to the ossified tendon of the M. ohliquus extemus of 
Marsupials. 
t They are so in the specimens killed at the time of capture; in two examples'kept for some time in capti- 
vity they are worn down to the base ; this was doubtless caused by efforts to escape, as we observe in other 
lizards under similar conditions. 
