512 TRANSACTIONS OF SECTION D. 
mandibles, and flying to and fro close by were two other wasps. These last 
attempted to alight on the nest, but as soon as they did so the wasp in 
possession opened its jaws, buzzed angrily, and made a rush at them, whereon 
they beat a hurried retreat. This happened many times. Closér examination 
showed that the wasp was guarding a small hole at one side of the nest, at 
which I could see the head of a newly-emerged imago at work gradually en- 
larging the opening. ... The confined imago made a sudden exit and fell, 
Lut the wasp on guard was so fully on the alert that it secured the falling 
insect with its legs and both came to the ground together. I am of opinion 
that it attempted to effect coitus, but in my anxiety to view satisfactorily the 
proceedings I approached too near, with the result that it took the alarm and 
flew up. I secured it, but the newly emerged wasp, the supposed female, 
escaped me. Meanwhile four more wasps were buzzing near the nest, and of 
these I managed to get two. I believe that these are males also, and I notice 
an astonishing difference in the degrees of mandibular development. The male 
with the largest pair obviously terrorised the others by virtue of possessing 
them, and, but for my interference, would have owed his success to this, for 
the case was definitely one of marriage by capture. The nest still contains three 
cells, and so I am hoping, if a female comes out, to be able to test for the 
assembling of males.’ 
It is impossible to imagine an observation that would have interested Charles 
Darwin more deeply than that recorded above by Mr. Lamborn. 
There can be no doubt that the species of wasp is Synagris cornuta Linn., 
the very name of which obviously refers to the enormous horn-like outgrowth 
trom the base of the mandible in some of the males. There is the same immense 
difference between the degrees of development spoken of by Mr. Lamborn, the 
outgrowth being of various sizes and sometimes only represented by a small 
tubercle. The females are very rare compared with the males—only one to 
about twenty in the British Museum of Natural History. Curiously enough, I 
had, only a few weeks ago, suggested observations on the part played in court- 
ship by the mandibles of these very males to another friend who had brought 
specimens home with him from Sierra Leone, and was returning later in the 
year. But Mr. Lamborn, with his wonderful powers of observation, does not 
let much escape him. 
It is suggested as a probable hypothesis that these immense horn-like out- 
growths sticking straight out in front of the face are a disadvantage in 
obtaining food and perhaps in other ways in the struggle for life, and that the 
emergence of the females covers a period long enough for this struggle to tell, 
so that the males with small or rudimentary horns have the advantage in the 
end through the operation of natural selection, while the others have the 
advantage at the beginning through sexual selection, in the form of battles 
between the males. 
I have written to Mr. Lamborn asking if he will carry out a series of 
observations in order to test this hypothesis. 
A remark of the late Edward Saunders, F.R.S., the great Hymenopterist, 
will indicate the impression made by these extraordinary male characters which 
might be taken for ‘monstrosities’ did we not know that they are normally 
present in many males. We were glancing through the boxes of his father’s 
collection in the Hope Department, at Oxford, when we came upon a male 
S. cornuta—a specimen from Fernando Po. ‘ Why,’ said Edward Saunders, 
‘it is a biological education to look at that insect!’ 
14. Note on the Habits and Building Organ of the Tubicolous Poly- 
chete Worm Pectinaria (Lagis) Koreni, Mgr. By Arnoup T. 
Watson, F.L.8S. 
The Amphictenide, of which family Pectinaria Koreni is a member, are 
admittedly the most skilful of marine tube-building worms. Their well-known 
tapering conical tubes, open at both ends, constructed generally of fine sand- 
grains, are examples of most exquisite and painstaking masonry. The worms 
are plentiful between half and extreme low tide marks on many sandy shores, 
through which they travel as was shown by the writer some nineteen years ago, 
