TRANSACTIONS OF SECTION D. 531 
on the sides of the vessel and among the bacteria in the surface film. The 
surface film food-source is so prolific that the Artemia spends much of its time 
feeding on it, and it is probable that the habit of swimming on its back adopted 
by Artemia is an adaptation for feeding in the surface film. 
In the lower strengths, 4 and 5, and in the higher, 20 and 25, either the eggs 
did not hatch or the young nauplii died as soon as the shell burst. Adults 
transferred from the optimum solutions 8 and 10 lived in the lower and higher 
strengths, and the eggs laid in these solutions by them lived and grew. This 
suggests that the cause of death in these extreme strengths in the first case was 
the sudden change in the osmotic pressure, since eggs will hatch in any solution 
in which they have been formed. 
No variation in the order described by Schmankiwitch was found in the 
second and third generations; the tail lobes were of uniform size in all strengths 
and possessed 8 spines on either side. It is probable therefore that variation 
is reduced to a minimum when the conditions and the relative percentages of 
the salt constituents in the solutions are constant, the variation in the total 
salt content of the water playing little part in the production of variations in 
structure. 
2. A Chalceid Parasitic on Thrips (Thysanoptera). 
By Ricuarp §. Baaenatn, F.L.S. 
. For some time now Thrips have been regarded as insects of considerable 
economic importance, and on that account have formed the subject of consider- 
able research. Yet it was only in 1911 that a parasite of any importance was 
discovered, when Mr. H. M. Russell reared a Hymenopterous insect belonging 
to the Chalcide from the prepupa of Heliothrips fasciatus Pergande, which Mr 
J. C. Crawford has described as a new genus and species, 7'Aripoctenus russelli. 
Mr. Russell last year published the results of numerous experiments carried 
out on this parasite, showing that it reproduces parthenogenetically and would 
oviposit in the larve of several species of Thrips belonging to the sub-order 
Terebrantia, such as Thrips tabaci, Vrankliniella tritici, but would not attempt 
oviposition in the larve of a species belonging to the sub-order Tubulifera, and 
also refused to oviposit in the young of a bug and of Aphides. 
In the same year (1911) G. del Guercio reported upon a Chalcid parasite of a 
species of Tubulifera, the Olive Thrips (Phlcothrips ole Costa); which in a 
later paper he named Tetrastichus gentilii, stating that both sexes occurred. 
With these exceptions only one other Thrips parasite has been named, when, 
in 1860, Mrs. Charlotte Taylor described one from Thrips on wheat, under the 
name of Pezomachus thripites, a small, wingless creature, with multi-articulate 
antenne and two thoracic nodes. This has not since been recognised. 
For some time I have observed a minute black and white Chalcid parasite 
which I have always regarded as having some connection with Terebrantian 
Thysanoptera. In August of this year (1913) I found many specimens of this 
Chalcid in the flowers of the toad-flax (Zinaria) at Hele Bay, near Ilfracombe, 
which were obviously interested in Thrips larve (Z’eniothrips primule chiefly, 
and Physothrips atratus), and the following morning, by a curious coincidence, 
I received a long-promised tube of 7hripoctenus russelli from Mr. Russell. An 
examination of my captures showed that they belonged to the genus 7'iripoctenus, 
and almost certainly to the American species, russelli, though I propose sub- 
mitting it to the describer, Mr. Crawford. 
British distribution of Thripoctenus russelli: August 1913, with Tniothrips 
primule and Physothrips atratus in toad-flax (Linaria), Hele Bay, near Ilfra- 
combe; with Oxythrips parviceps and Physothrips erice in heather on the Tors, 
near Ilfracombe, and with Thrips tabaci, Frankliniella intonsa and Thrips 
palustris in the louse-wort (Pedicularia palustris) at Hogley Bog, Cowley, near 
Oxford. 
3. On the Systematic Position of the Order Protura. 
By Ricuarp §. Baenauy, F.L.S. 
The Order Protura, diagnosed by Silvestri in 1907 and monographed by 
Berlese two years later, on account of its anomalous nature and curious morpho- 
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