THE CHELONIA. 1015 
gait of similar character, the humerus being never depressed 
below a horizontal position and moving in a plane which, although 
t does fall towards the back, is more nearly horizontal than 
vertical. These animals certainly swayed from side to side whilst 
walking. 
The Chelonian humerus can be directly derived from the 
reptilian humerus as represented by Varanosaurus. The rounded 
and upturned head is an obvious adaptation to the retraction of 
the limbs. The narrow distal end, so different from the wide 
epicondyyar region of the early forms, depends on the reduction of 
the muscles which lie along the lower surface of the fore arm, and 
are inserted on the entepicondyle, following on the habit, induced 
by the developing shell, of carrying the fore arm vertically. 
The short, powerful, downwardly directed radial and ulnar crests 
seem to depend to some extent, though not completely, on the 
development of the shell as a source of muscle-attachments. 
We may, in fact, take it as probable that ‘ Archichelone” had 
limbs more or less like Zryops or Varanosaurus or Dimetrodon. 
Hunotosaurus africanus Seeley is at present represented by five 
specimens, one of which is in the South African Museum, Cape 
Town, and the other four in the British Museum (Natural 
History). All these specimens agree in including only the dorsal 
region of the animal, and except in the case of the type are 
preserved in nodules, so that in transverse section the ribs form 
an oval rather higher than wide. 
The most nearly complete is No. R. 4054, B.M.N.H. (PI. VII. 
figs. 3 & 4). This is preserved in a very hard nodule and shows the 
general shape. At the anterior end a scapula is in place on one 
side; onthe other end of the specimen we have the impression of 
the anterior face of the first sacral ribs and of the anterior border 
of the ilia. The specimen is thus of importance, because it shows 
that the entire dorsal region is preserved. 
No. 49424, which is also preserved uncrushed in a nodule, 
is not quite complete behind, but in front the shoulder-girdle is 
shown in part. The skull lies with its ventral surface in contact 
with the ventral surface of the body and with its anterior end 
pointed backwards, with the lower jaw articulated. ° 
Weathering has. removed the whole skull to within about a 
millimetre of the dorsal surface of the palate and in the middle 
has even removed the bone from this, leaving a somewhat faint 
impression. ‘This specimen is important, because it alone shows 
the skull and because the position of the head is only possible if 
the neck were fairly long and flexible. 
No. 49423 (Pl. VIL. fies, 1 & 2) is a specimen Tote twice the 
size of the preceding two, and like them preserved uncrushed. 
It shows, well preserved, the whole shoulder-girdle and also im- 
pressions of the humeri from which the bone has weathered 
away. It also shows traces of scutes. 
No. R. 1968. The type-specimen differs from all the otliers in 
