Ji26 INSECTA. 
Wood, J. G. Insects at Home : being a Popular Account of 
British Insects^ their Structures, Habits, and Transforma- 
tions. London ; 1872, pp.670, plates and many woodcuts. 
On the study of entomology ; J. A. Harker, Scot. Nat. i. pp. 249-254. 
On the danger of generalizing from too limited an area, as exemplified 
in entomology. H. T. Stainton, Ent. Ann. 1873, p. 83 et seq. 
Fossil insects. S. H. Scudder, Am. Nat. vi. pp. 666-668, records 39 certain 
species from shale near the junction of the Green and White Rivers, Colo- 
rado (Wyoming), chiefly Diptcra and Coleoptera. Exact particulars of the 
discovery of these insects are given by F. 0. A. Richardson, ibid. p. 666, 
note. The species of Mycetophilidce and Tipididce agree best with other fossils 
from the tertiary beds of the same region. 
Insect-origin. B. T. Lowne, Nature, v. p. 183 j A. R. Wallace, Presid. 
Address, E. Soc. Lond., Anniv. 1872, ibid. p. 350 j J. J. Murphy, Nature, 
vi. p. 373; F. B. White, ibid. p. 393; Belpino, Bull. Ent. Ital. iv. p. 342 
et seq. ; (and Geology) G. Schoch, MT. schw. ent. Ges. iv. pp. 25-29. 
Physiology. The primitive element of muscle is a cell, which, by elon- 
gation, forms a fibre. Kunckel, OR. Ac. Sc. 6 Aug. 1872, R. Z. (2) xxiii. 
p. 454. 
In Bull. Ent. Ital. iv. pp. 176-186, pi. 2. figs. 2-10, are some notes by 
A. Targioni-Tozzetti on the internal anatomy of insects, chiefly concern- 
ing a form of epithelial cell found in the intestinal tube of the larva of Apis 
ligustica, which is compared with a corresponding form in Oniscus. 
Theory as to the origin of wings : OR. Ent. Belg. xv. p. Ixv. 
The tracheae have no respiratory function in aquatic larvae, which breathe 
like other aquatic animals. They merely keep a uniform layer of air under 
the skin of the pupa, so as to prevent friction. The respiratory organs of 
the pupa accumulate a quantity of air in the oesophagus, which, emitted 
suddenly from the anus, assists mechanically in the exclusion of the perfect 
insect. Monnier, OR. Ac. Sc. 22 Jan. 1872 ; 11. Z. (2) xxiii. p. 231. 
Terrestrial Coleoptera resist asphyxia from submersion for periods varying 
up to nearly 100 hours. Aquatic species (and aquatic Hemipterd) perish 
sooner, possibly on account of their greater activity in the water, accompanied 
by a greater loss of ox 3 ^gen. Aquatic insects resist cold, at zero, for an inde- 
finite time, but rapidly die in ice, on account of their being entirely deprived 
of movement. The higher temperatures supported in safety by insects are 
very limited in extent, corresponding with those of certain known thermal 
springs in which Articulata are found. These observations apply to tempe- 
rate Europe. F. Plateau, Bull. Ac. Belg. xxxiv. nos. 9 & 10. 
Life in salt and fresh water. In R. Z. (2) xxiii. p, 73, reporting OR. Ac. 
Sc. July 1871, is an analysis, by the same author, of his ‘^Recherches phy- 
sico-chimiques sur les Articules aquatiques,” as follows : — Freshwater ArticU’- 
lata, with thick integument and no branchiae, live with impunity in salt 
water, in which those with thin skin and branchial respiration die quickly, 
the combinations of sodium and magnesium acting as poison ; saltwater 
Crustacea die in fresh water, as the salts necessary for their existence are 
taken up in it from their tissues. Difference of density is immaterial. 
