SECTIONAL TRANSACTIONS.—D. 319 
- —as in Anabas, Macropodus, and Ophiocephalus ; it is present, but less developed, in 
_ Clarias and Saccobranchus; but it may be completely absent—as in Amphipnous. 
The function of this original air-bladder is now chiefly hydrostatic, though it was 
originally respiratory and gave rise to the lungs of Dipnoi, but the air-breathing 
apparatus described in this paper is quite new and an independently evolved structure 
appearing secondarily during the post-larval history of the fish in relation to its 
special mode of life. 
2. Prof. E. W. MacBripg, F.R.S.—The Migratory Habits of Echino- 
cardium. 
The genus Echinocardium is taken by Petersen as characteristic of one type of the 
series of animal communities which he has described as occupying definite territories 
all over the bottom of the North Sea. The two species, H.cordatum and ZL. flavescens, 
are abundant throughout this area, and each is characteristic of a certain type of 
community. Under these circumstances the habits of each species become of 
importance and interest. . cordatum is found within tide marks on sandy beaches 
all along our western coast, and is particularly abundant just above the limit of low 
spring tides in Harlech Bay, which I visit every summer. It is found occupying a 
burrow about three inches below the surface of the sand, communicating with the 
surface by a vertical shaft, up which it extends its long tube feet in order to gather 
food. Yet no specimens less than four inches in length could be found. From 
previous work it is known that the young urchin, just after metamorphosis, is only 
$% m.m. in length, yet the most diligent sifting of the sand through fine sieves failed to 
reveal intermediate stages. Mr. Elmhirst, Curator of Millport Biological Station, 
at my request, sifted the sands of Kaines Bay, Millport, where the adult is abundant, 
with a like negative result. On the other hand, Dr. Mortensen sent me an abundant 
supply of the stages I sought, dredged from deep water. It is clear, therefore, that 
the abundant adult forms must have migrated into their present positions—in a word, 
that the animal does not remain constantly in its burrow, but at high tide comes up 
to the top and walks about. 
3. Mr. Joun F. Marsuary.—Coastal Mosquitoes and their Control. 
The unpopularity of mosquitoes arises partly from (1) the power possessed by 
certain groups only of conveying definite diseases (e.g. malaria) from man to man, and 
partly from (2) their power of creating a, widespread nuisance on account of the 
general annoyance caused by their bites and the various unpleasant consequences. 
Nowadays, in Great Britain, the ‘malaria-carrying’ aspect of mosquitoes 
demands little more than academic consideration : yet it was not until the year 1920 
that any systematic attempt to control the mosquito from the purely ‘ nuisance ’ 
point of view was made in this country. In that year the Hayling Mosquito Control 
was formed ; and, three years later, a similar organisation was initiated at Alverstoke 
(Hants). In both of these districts a serious and longstanding mosquito nuisance 
has completely disappeared. 
It has been known for a quarter of a century that mosquitoes can only be con- 
trolled successfully before, or during, their larval stage, by engineering or chemical 
means respectively. The abolition of stagnant water (by draining, filling-in, &c.) 
is obviously the most effective method, but, where extensive breeding areas are con- 
cerned, the cost of such work is frequently prohibitive. In such cases, an alternative 
scheme is to establish some form of centralised ‘ intelligence system,’ by means of 
which possible breeding places can be inspected periodically and dealt with as occasion 
arises. 
4. Mr. F. W. Epwarps.—A Marine Chironomid Fly from Samoa. 
The insects described in this paper were taken in a tow-net over the coral reef at 
Apia, Samoa, by Dr. P. A. Buxton in 1925. The species shows an extraordinary 
degree of sexual dimorphism, the females being worm-like, though the males have well- 
developed legs, antennz, and mouth-parts. This latter sex also possesses wings of a 
peculiar form, which seem to indicate a definite adaptation to life under water, and it 
is highly probable that the whole life of the species is passed actually in the sea, which 
is not known to be the case in any other insect, although some other members of the 
family Chironomidz have marine larve and pup. 
