neuropterous insects. 
41 
But it varies much in color. The vittae of the 
abdomen are more or less dilated, sometimes hardly 
visible ; the head and thorax are, in some indivi- 
duals pearlaceous-blue, and the ultimate abdominal 
segment varies from dull yellowish, with blackish 
lines, to a bright pearl-blue, sometimes dull-yellow- 
ish with a pearlaceous-blue lateral spot on each. 
It is very common. 
The female has two small angulated processes 
beneath the tail, which do not extend beyond the 
tip of the abdomen, the nails at their extremities 
are curved downwards ; the hooks at the tip of the 
abdomen of the male are not obvious. 
The description is from recent specimens. The 
fine blue color disappears in the cabinet specimen. 
B^etis, Leach. 
1. B. interpunctata. Whitish; head greenish; 
segments of the tergum black on the posterior edges. 
Inhabits Indiana. 
Body yellowish-white, tinged with green ; head 
rather prominent, yellow-green ; vertex with a la- 
teral black point ; eyes with a longitudinal black 
line , stemmata distant, each with a black orbit ; 
anterior one less than half the size of the others ; 
seta of the antenna; black ; front with a black angu- 
lar line under the antennae ; neck distinct, sepa- 
rating the head from the trunk, with a black line 
each side ; thorax somewhat brownish ; wings on 
the anterior margin greenish, with black cross ner- 
vures, and a distinct, black, abbreviated, longitudinal 
VOL. vin. — 1839. 6 
