(abe D 
from its frequently furnishing in its sculpture undeviating 
specific characters in several genera, wherein colour either 
affords none or very unsatisfactory ones. I understand it 
similar to Kirby and Spence, to comprise the whole of the 
thorax beyond the post dorsolum. It is frequently sepa- 
rated into two divisions, the anterior portion forming a 
semicircular, triangular or subcordate plate with an elevated 
margin. It is generally obtuse at its extremity, but occa- 
sionally truncated, and then sometimes armed on each side 
with a spine (Vysson, Alyson). In Oxybelus it has a central 
curved mucro in its centre at its origin, with a lanceolate 
process on each side, and it is occasionally pubescent. The 
MESOSTERNUM has in some species a spine on each side 
posteriorly, and this not sexual but common to both; the 
uses of these tubercles and spines is exceedingly difficult 
to imagine, no satisfactory explanation of them has ever 
suggested itself to me. Of the organs of locomotion the 
Wines must decidedly rank foremost in these insects. I have 
already shown above their importance in the generic division 
of this tribe, but it is only a portion of them which has 
hitherto been thus applied, viz. those nervures marked in 
dots in the second figure of the first plate of this book, 
which will be found quite sufficient for all the purposes of 
British Entomology. In a paper of mine recently read at 
the Entomological Society, I have examined the distribu- 
tion of the nervures upon the superior wing and the rules 
which seem to regulate it. In the nomenclature I adhere 
to that of my predecessors, unless at all at variance with 
the course nature seems to have pursued in their structure, 
which I follow as closely as the clue admits. I refer, con- 
sequently, to that paper for the detail of my investigation, 
and shall retain here merely the names of the parts, to illus- 
trate which, I have added a coloured figure, which shows 
