TESTUDO RADIATA. 
tentoria , and although, as in these species, the yellow markings and lines are 
disposed in radii, yet there are some remarkable peculiarities, even in this re¬ 
spect, which it may he useful to particularize. One of the most striking of 
these is that all the yellow radii, which in T. geometrica are linear, have, in this 
species, a remarkable disposition to expand towards the circumference. The 
proportional quantity of yellow varies exceedingly in different specimens, not 
only from the different breadth, but also from the variable number of the 
radii; but however they may differ in this respect, there are certain characters 
about the direction of the markings and the essential existence of some of them, 
which are at once so constant and so characteristic as to require a more 
detailed description. 
The areolae are, without exception, yellow or yellowish brown, and the 
radii spring from them as from a centre, and pass straight to the circumference, 
expanding regularly to their termination. They do not, as in geometrica , ac¬ 
curately meet those of the contiguous plates. The first vertebral scutum has 
always one ray at each of the four principal angles, and often a few smaller 
ones on the hinder section : in the second and third, the radii are more nume¬ 
rous, but almost entirely restricted to the sides, towards the costal plates : the 
fourth has the lateral and posterior segments occupied by them, with very few 
and slender ones on the anterior: those of the fifth are restricted to the ante¬ 
rior and posterior segments. The first costal plate has two small rays in the 
direction of the two superior angles, and numerous broader ones extending to 
the marginal plates : the second and third have three passing to the three 
superior angles, and four or more downwards to the margin: the fourth has 
two superior and several inferior rays; but in the costal plates there is scarcely 
a trace of rays passing laterally from one to the other. The rays of the mar¬ 
ginal plates are directed upwards from the areolae, which are placed at the 
very margin of the shell; they spread upwards in the shape of a fan, diverging 
as well as expanding to their termination. The nuchal plate has in some 
specimens one slender ray; in others it is wholly black. The caudal follows 
the iule of the marginal plates. In the sternum, the yellow colour obtains 
much more considerably than on the upper shell. The gular plates are almost 
wholly yellow, excepting a small ray or two of black, and, with the yellow 
