864 ReEvorT— 1890. 
The most important conclusion to be drawn from this investigation is that as 
regards the position and general character of the gonads M7llepora is not related 
to any of the known Stylasteride. 
It may be added further, that the more completely the anatomy of Millepora is 
known, the more sharply is the line defined that separates M2llepora from all the 
other Hydrocoralline. 
8. On the male Gonangia of Distichopora and Allopora. 
By 8. J. Hickson, M.A., D.Sc. 
The author can find no reference by any previous writer to the male sporosacs 
of Distichopora. 
Those of Allopora were discovered and described by Moseley. 
In Allopora the sperm sacs lie between the endoderm and ectoderm of club- 
shaped, czecal diverticula of the canal system, that are given off some distance 
below the surface of the corallum. They are not visible, therefore, in specimens 
previous to decalcification. 
In Distichopora these diverticula are not so long and prominent. They are 
usually grouped together in threes and fours, and lie immediately beneath the 
surface, so that they are when mature quite visible before decalcification. Moseley 
calls attention to tail-like processes on the distal extremity of the sperm sacs in 
Sporadopora. ‘These are, when the spermatozoa are mature, two cell-layered tubes 
opening to the exterior for the escape of the spermatozoa. Similar structures 
occur in Distichopora, but they are not so long, as the ampulle are more super- 
ficial, 
9. On the Tracheal Occlusor Apparatus in Insecta. 
By Professor A. Denny. 
10. The Life-History of the Hessian Fly, Cecidomyia Destructor (Say). 
By ¥F. Enocx., F.E.S. 
Though nearly a hundred papers of various lengths have been written by 
American, English, German, and Russian entomologists since the Llessian Fly 
first made its appearance in Long Island about the year 1778, few of the authors 
have done much else than copy each other’s accounts, showing that their observa- 
tions have not been made in the field of Nature; and it is only by the most careful 
and patient watching that we can collect the various links required to form a com- 
plete life-history. 
In a brief abstract on such a subject as the life-history of so important an 
insect as the Hessian Fly it is impossible to do anything like justice to it or give 
more than a few facts. 
The Hessian Fly generally makes its appearance towards the end of April, 
continuing through May, June, and a considerable part of July, the main brood 
laying eggs in May in the ridges of the lower leaves of wheat and barley. Each 
female lays from 100 to 150 eggs, which hatch in four days, the young larve 
working their way down the leaf, and between the sheath and stem, until they 
arrive just above the joint. Here they fix themselves head downwards and 
towards the stem, the juices of which they imbibe, so weakening the plant that _ 
it is unable to bear the weight of the partly formed ear, the stalk bending down 
at the injured joint, generally stopping further development, and so impoyerishing 
the ear that the grain does not come to perfection. 
After feeding for about three weeks the larva assumes the so-called ‘ flax-seed” 
state ; the outer skin gradually changes from white to chestnut colour, becoming 
hard and somewhat brittle. At the same time that this drying-up and change of 
colour has been going on a wonderful change has taken place within, the larva 
shrinking and becoming entirely free, though still surrounded by the hardened skin 
of the original larva. The mouth-organs of the internal larva are not much 
