INSECTA — ORTHOPTERA. 
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variations; Perla hipunctata has, in the intestinal canal, a ring of 
eight blind sacs at the end of the stomach, a caecum, and numerous gall 
vessels ; in other species the number of the latter is less ; in Chloroperla 
the blind sacs are small, and reduced to six in number, the caecum is 
wanting, and the gall vessels are only twenty, and much shortened ; in 
Nemoura the blind sacs are wanting, and the gall vessels are still fewer. 
Similar variations occur in the form of the under lip, as the parts pointed 
out by me as lobes, appear to vary in their extent of development. 
Pictet has had the advantage of a very great supply of species, 
so that this formerly small family has now arrived at considerable size. 
Twenty-eight of the species described are still unknown to him ; the 
number of those examined by him amount to 100, of which nearly two- 
thirds are new. Of these 100 species, twenty-seven are spread over a 
great portion of Europe ; nine are peculiar to Switzerland, six to the 
north, and nine to the south of that country. There are two Egyptian 
species ; eight from Asia, viz., — one Siberian, one from the continent 
of India, two from the Sunda Islands, four from Japan. There are two 
species from New Holland. America has, in all, thirty-seven, viz., — seven- 
teen from the United States, five from Mexico and Columbia, three from 
Chili, ten from Brazil, and two inhabit a great part of that continent. 
Pictet recognises six genera, which are partly divided into sub-genera. 
I. Kollaria, new genus, with setaceous very long maxillary-palpi, a 
very large projecting external maxillary lobe, small mandibles, and 
large netted and veined wings. One species of considerable size, of 
which the native country is unknown. 
II. Pteronarcys, Newm., netted and veined wings, short setaceous 
maxillary palpi, of which the second, third, and fourth joints, are dilated 
externally. Pt. protceus, N., and Perla reticulata, Burm., and Pt. 
thalia, regalis, and hiloba, Newm. 
III. Eusthenia, Westw., strong netted and veined wings, moderately 
long simple setaceous maxillary-palpi. E. spectabilis, Westw., from 
the Swan River. 
IV. Perla, Geoffr., simply veined wings, setaceous palpi. Contains the 
following sub-genera : — 1. Dictyopteryx ; the terminal part of the sub- 
marginal space crossed by transverse nerves ; the longitudinal nerves 
there are often irregular, the wings rounded, the head small ; P. microce- 
phala, Piet. ; and five new species. — 2. Nephelion ; the terminal part of 
the sub-marginal space without transverse nerves ; but the branch of the 
sub-marginal nerve ramifies considerably, and is irregular : Isogenus 
nubecula and frontalis, Newm., and two new species. — 3. Acroneuria ; 
wings elongated with the terminal part of the sub-marginal space crossed 
by transverse nerves; and the longitudinal nerves are irregular; head 
broad ; mandibles with one tooth : one new species, P. arenosa, from 
North America, which perhaps may be united to P. abnormis, Newm. — 
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