144 Proceedings of the Royal Physical Society, 
is large and measures about one-sixth of the whole length of the specimen. 
It is deeply arched, much narrower in front than behind, while its large 
side lappets extend backwards behind the main body of the tergite itself, 
and even to beyond those of the succeeding tergite. The anterior and 
antero-lateral margin is somewhat thickened, and followed immediately 
behind by a comparatively wide shallow groove which is continued into 
the side lappets. Behind the groove the body of the tergite becomes 
suddenly swollen, and rises into a rounded boss at the base of the side 
lappet. The posterior margin, extending between the bases of the side 
lappets, is simply a sharp doubling back of the test to form the articular 
surface under which the anterior part of the succeeding segment rolled. 
Larger pores than those found on the rest of the test can be traced along 
the shallow groove bordering the front part of the tergite. 
3rd Tergite.—This tergite, which in the specimen is somewhat telescoped 
beneath the former one, measures only about a twenty-fourth of the whole 
length of the specimen. It tapers downwards, and only reaches down to 
about the base of the side lappets of the second tergite under which it rolls, 
while posteriorly it is sharply bent inwards and forwards to form the 
articulation under which the succeeding tergite folds in turn. 
4th Tergite—This tergite is in most respects similar to its predecessor. 
It is slightly wider than it and reaches farther down the sides and bears 
small side lappets which appear to be bevelled in front, though, owing to 
a slight bend of the body of the specimen, this part is concealed by the 
backward extending side lappets of the nuchal tergite. The nature and 
arrangement of its articulations with adjoining tergites are like those of its 
immediate predecessor. 
5th to 8th Tergite.—These tergites are all similar to each other im most 
respects, except that they gradually increase in length and depth. The 
length of the eighth tergite is about one-ninth of the whole specimen. The 
articulations with each other are identical with those of the fourth tergite, 
while the side lappets are each bevelled off in front to allow of rolling. 
9th to 13th Tergite—These tergites are precisely similar to those just 
described, only they rapidly decrease in size so that the length of the 
thirteenth is less than half that of the eighth. 
14th Tergite—The terminal tergite is simple and makes nearly the 
quarter of a hollow sphere, and is similar in all respects to the terminal one 
in recent rolling Millipedes, except that it is relatively smaller. In the 
present specimen it measures along the curve of the back only about 
one-sixth of the whole length of the specimen, whereas in Sphwrotheriwm 
it measures nearly one-third of the length of corresponding parts. 
