342 
Transactions of the Society. 
The extremities of the Corethra larva are certain to attract the 
attention of the casual observer : the anal segment on account of 
its beautifully plumed fin, and the head because of its array of 
appendages. Most of the latter are employed in hustling the 
captured crustacean into its capacious jaws. Once inside the mouth, 
escape is almost impossible. In addition to the interlocking of the 
finger-like processes on the jaws, there is a suspended screen at the 
entrance of the mouth, consisting of a number of long chitinous 
spines, which come into play during the process of passing on the 
prey, and this prevents any slipping out before the jaws are closed. 
There are no further hairs in the throat — a clear way exists 
along the whole of the pharyngeal tube. The juices from the 
salivary glands then come into play, assisted by a peristaltic 
movement of the pharyngeal tube, and the food is dealt with. Any 
indigestible portions, such as the carapace of the water flea, are 
thrown out by a voluntary action, the ejection being brought 
about by the eversion of the pharyngeal tube, a rather drastic 
method for such a simple operation. 
On closer examination, it will be noticed that unless reduced 
to small fragments, the food cannot be passed from the pharyngeal 
tube to the stomach on account of the oesophagus which inter- 
venes, consisting of a transparent tube of exceedingly small 
diameter. 
Before leaving the head we will refer to the pair of small black 
pigment spots immediately behind the large compound eyes. These 
spots persist during the larval stage, and can be seen in the pupa, 
appearing at the back of the eyes in the perfect insect. 
After many failures we captured and mounted our first young 
specimen. Its length was 2 mm. The only indication of an eye 
was the black pigment spot, but the amount of light gathered in 
its area when viewed under the microscope suggested a lens, and, 
on gently warming the slide, we succeeded in scattering the black 
granules forming the pigment spot, revealing the lens which had 
hitherto escaped notice. (See PL XVII., fig. 18.) 
The next specimen we mounted measured 5 mm., and at this 
stage of its development the large compound eye was about one- 
third grown. From this it will be judged the young larvae have 
to rely on the simple eye for quite a period after they are hatched. 
The adult measurement averages 13 mm. — at 5 mm. it would be 
about half-grown. 
It was whilst attempting to catch these very small creatures 
with a pipette that we appreciated the difficulties of landing them 
were similar to those experienced in endeavouring to take the 
fully grown forms, which are provided with two additional large 
-compound eyes. 
It is also interesting to note that the head of the fully grown 
larva is somewhat wedge-shaped, the compound eyes being placed 
