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lar pieces, between which the unusually developed thirteenth seg- 
ment appears. These lateral portions are fringed with spines on 
the posterior two-thirds of their inner margin, and the segment is 
longitudinally divided beneath. These two segments together are 
about one and a half times the length of the preceding. Their 
dorsal portions are likewise elongate, as compared with the other 
species, being scarcely, if at all, shorter than the next segment in 
advance. 
In the form of the mouth parts, this root-worm is lhkewise distin- 
guished from at least one of the others, the tips of the mandibles 
in Scelodonta (Plate IX, Fig. 1, C), being entire with their inner 
margins excavated a little above the tips; while in Colaspis the 
mandibles are bifid at the tip, (Plate IX, Fig. 4, C), and the inner 
margins are uniformly curved. 
It is in these latter structures only that any character can 
be found by which the larva of Scelodonta may be separated 
from that of Paria. In every other minutest particular of form and 
structure, even to the number, distribution and arrangement of the 
hairs upon the surface, these two larve agree precisely. But 
while the tips of the mandibles of Scelodonta are either entire, 
or, if notched, are so lobed that the central division is much the 
longest, those of Paria (Plate IX, Fig. 5, B,) are obtuse at the 
extremity and distinctly emarginate, being sometimes deeply bifid. 
It must be confessed, however, that none but an expert will be 
able to distinguish between these two. species in the larval stage; 
and it is not impossible that this trivial character will be found too 
variable to be depended on, except where a considerable number of 
specimens are studied together. 
The pupze may be separated by differences in the armature of 
the posterior segments of the abdomen, especially the last. This 
segment in the pupa of Colaspis, (Plate IX, Fig. =, F,) terminates 
in two simple hooks, the points of which curve towards each other, 
while in both Paria (Fig. 5, A) and Scelodonta (Fig. 1, A) these 
hooks are larger and longer, and curve dorsally instead of inwards. 
In front of these hooks are two pairs of lateral spines, one attached 
to the ultimate segment and the other to the penultimate, the for- 
mer of which in Colaspis extend directly outward, while in the other 
larve they project backward instead. 
There are likewise slight differences in the spines upon the knees 
of the pupa. In Colaspis a strong curved hook arises from the 
anterior inferior angle of the tibio-femoral articulation of all the 
legs, that of the anterior pair being, however, very small. In Scelo- 
donta and Paria, on the other hand, we have a stout spine upon 
the posterior legs, but the corresponding angles of the two anterior 
pairs are unarmed. 
The most careful comparison of the pup of the two more closely 
related species, has enabled me to detect only a single difference 
between them. In Scelodonta (Fig. 1, A) the terminal abdominal 
hooks have each a strong, erect tooth or spine attached to the upper 
side of the base while in Paria (Fig. 5, A) this spine is wanting. 
