494. ONISCIDA. 
under a strong magnifying power the rudiments of two 
very minute terminal joints are to be perceived, as well 
as several short thickish spines. The large outer antennze 
are seven-jointed, the second joint roundly dilated at its 
outer edge at the tip, the fifth joint long, the seventh the 
slenderest, with a minute distinct seta at the tip. 
The third segment of the tail is laterally continuous 
with the edge of the seventh segment of the body, the 
two basal segments of the former, although quite dis- 
tinct, being short and greatly abbreviated at the sides. 
The hind margin of the fifth segment is semicircular, 
the emargination being filled in by the small triangular 
sixth segment, of which the apex is obtuse, and by the 
flattened and truncated outer division of the first pair of 
false legs, the inner division being small, flattened, and 
ovate. The five anterior pairs of appendages of the tail 
differ considerably in form, the first pair being composed 
of two flattened, somewhat triangular, plates ; the second 
pair in the male is nearly similar in form, but is provided 
with a large pair of elongated horny lobes, slightly 
curved at the tips; the third pair in the male is more 
sabre-shaped, with a slender horny appendage, having the 
tip bent and acute; the fourth, fifth, and sixth pairs have 
the plates triangular-shaped. 
The general colour is leaden, or dark steel-grey, with 
spots and patches of dull buff or whitish: it varies, 
however, to brownish testaceous. It inhabits rather dry 
places under stones, decaying timber, and among herbage, 
and is often seen running about foot-paths, rolling itself 
up into a ball at the least alarm. This has gained for it 
the name of Pill millepede, and in ‘‘ former times it was 
highly reputed for its supposed medicinal virtues, the 
old books of Materia Medica informing us that when 
dried and pulverized they have a faint disagreeable 

