LOWER LIAS. 
19 
and 1 inch 3 lines across from before backwards. On the middle of the outer 
border is a tuberosity; each side of the distal end is deeply impressed ; the distal 
artic Illation resembles that in the second toe. The greatest transverse breadth of 
this phalanx is 1 inch 7 lines. The second phalanx (ib., 2j, with a basal breadth 
of 1 inch 6 lines, is only i incli 7 lines in length. The distal articulation is 1 inch 
5 lines in breadth. The third phalanx (ib., 3 ), with a basal breadth of 1 inch 3 
lines, is i inch 2 lines in length, with a distal breadth 1 inch 1 line. The ungual 
phalanx (ib. -t) is more depressed in proportion to its breadth than that of the 
preceding toe ; in other respects it resembles it in shape. 
The fourth metatarsal (ib., w), is 4 inches 5 lines in length, of an unsymmetrical 
figure, receding from the middle metatarsal along its distal half, which is concave 
lengthwise on the tibial side ; the fibular side presents a general but slighter con- 
cavity ; this metatarsal is triedral, the fore and back surfaces converging to an 
obtuse, narrowg outer border, significant of its terminating that side of the foot 
beyond the representative style of the fifth digit ( v ). The fourth metatarsal 
measures 1 inch 9 lines across the base and 1 inch 7 lines from before backwards, 
at the tibial side of the base ; the fibular side being reduced to the narrow rough 
ridge for the ligamentous attachment of the fifth abortive metatarsal. The breadth 
of the shaft of the fourth metatarsal at its lower third is 1 inch 1 line ; that of the 
distal articular surface is 1 inch 5 lines. The first phalanx of the fourth toe is 
1 inch 11 lines in length ; the basal breadth is 1 inch 8 lines and the distal breadth is 
1 inch 5 lines. The tibial angle of the proximal surface is most produced. The 
fore-and-aft dimensions of the shaft do not exceed 6 lines. The second phalanx 
is 1 inch 2 lines in length, and 1 inch 3 lines in basal breadth. The third phalanx 
is 1 inch in length, 1 inch 4 lines in breadth ; the fourth phalanx is 9 lines in 
length, ] inch 2 lines in breadth. The ungual phalanx is 1 inch 6 lines in length; 
8 lines across its articular surface, 1 1 lines across its broadest part, caused by the 
aliform expansions of the bone beyond the articulation. It curves downwards and 
inwards, or towards the tibial side, to a subacute apex ; the characters of its 
surface correspond with those of the larger ungual phalanges of the preceding toes. 
From the abortion of the fifth digit, and the disproportionate shortness of the 
first, we have in Scelidosaurus the example of a reptile manifesting a tendency to 
the tridactyle type of the hind foot, and this is effected in its remote successor of 
the Wealden period, — the Iguanodon, by the suppression of the first, and by a 
similar atrophy of the fifth digit. The foot-prints of Scelidosaurus would termi- 
nate forward by the marks of four claws, the innermost falling short of the base 
of the second, this and the fourth reaching the same line, and the intermediate 
third claw extending farthest. The hind foot-prints of Iguanodon would be 
tridactyle. 
The total length of the foot of Scelidosaurus is 1 foot 1 inch 6 lines ; the 
